From 72c8646956ffc8050bb8be5988a0f28fc37e1ac4 Mon Sep 17 00:00:00 2001 From: Martin Kaiser Date: Thu, 25 Jun 2026 08:34:45 +0900 Subject: tracing: probes: fix typo in a log message Fix a typo ("Invalid $-variable") in a log message. Link: https://lore.kernel.org/all/20260507081041.885781-4-martin@kaiser.cx/ Fixes: ab105a4fb894 ("tracing: Use tracing error_log with probe events") Signed-off-by: Martin Kaiser Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_probe.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 15758cc11fc6..0f09f7aaf93f 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -511,7 +511,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, C(NO_RETVAL, "This function returns 'void' type"), \ C(BAD_STACK_NUM, "Invalid stack number"), \ C(BAD_ARG_NUM, "Invalid argument number"), \ - C(BAD_VAR, "Invalid $-valiable specified"), \ + C(BAD_VAR, "Invalid $-variable specified"), \ C(BAD_REG_NAME, "Invalid register name"), \ C(BAD_MEM_ADDR, "Invalid memory address"), \ C(BAD_IMM, "Invalid immediate value"), \ -- cgit v1.2.3 From 931a577fc79ea6a169a33f5538f4c1433235c358 Mon Sep 17 00:00:00 2001 From: Yiyang Chen Date: Tue, 23 Jun 2026 06:11:09 +0000 Subject: bpf: Reject offset refcount acquire arguments bpf_refcount_acquire() increments the refcount at the caller-supplied pointer plus the refcount field offset, then returns the caller-supplied pointer unchanged. The verifier records the return value as a base pointer to the refcounted object. bpf_list_pop_front() and bpf_rbtree_remove() can return embedded graph-node pointers as PTR_TO_BTF_ID | MEM_ALLOC with a fixed offset equal to the node field offset. Passing such a pointer directly to bpf_refcount_acquire() currently passes the refcounted-kptr type check. That makes the runtime operation start from base + node_off while the verifier models the returned pointer as the object base. Require refcount-acquire arguments to have zero fixed offset by carrying the requirement through check_func_arg_reg_off() to __check_ptr_off_reg(). Programs can still acquire a refcount from a graph-node-derived pointer after normalizing it with container_of(). Fixes: 7c50b1cb76aca ("bpf: Add bpf_refcount_acquire kfunc") Signed-off-by: Yiyang Chen Acked-by: Eduard Zingerman Acked-by: Yonghong Song Link: https://lore.kernel.org/r/2f894647f56f71838fdddeb97a3e057ed35ea92e.1782192383.git.chenyy23@mails.tsinghua.edu.cn Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 21a365d436a5..3cdc2e90f643 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7996,9 +7996,10 @@ reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields) return field; } -static int check_func_arg_reg_off(struct bpf_verifier_env *env, - const struct bpf_reg_state *reg, argno_t argno, - enum bpf_arg_type arg_type) +static int __check_func_arg_reg_off(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, argno_t argno, + enum bpf_arg_type arg_type, + bool btf_id_fixed_off_ok) { u32 type = reg->type; @@ -8055,12 +8056,11 @@ static int check_func_arg_reg_off(struct bpf_verifier_env *env, case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU: /* When referenced PTR_TO_BTF_ID is passed to release function, * its fixed offset must be 0. In the other cases, fixed offset - * can be non-zero. This was already checked above. So pass - * fixed_off_ok as true to allow fixed offset for all other - * cases. var_off always must be 0 for PTR_TO_BTF_ID, hence we - * still need to do checks instead of returning. + * can be non-zero unless the caller requires otherwise. + * var_off always must be 0 for PTR_TO_BTF_ID, hence we still + * need to do checks instead of returning. */ - return __check_ptr_off_reg(env, reg, argno, true); + return __check_ptr_off_reg(env, reg, argno, btf_id_fixed_off_ok); case PTR_TO_CTX: /* * Allow fixed and variable offsets for syscall context, but @@ -8076,6 +8076,13 @@ static int check_func_arg_reg_off(struct bpf_verifier_env *env, } } +static int check_func_arg_reg_off(struct bpf_verifier_env *env, + const struct bpf_reg_state *reg, argno_t argno, + enum bpf_arg_type arg_type) +{ + return __check_func_arg_reg_off(env, reg, argno, arg_type, true); +} + static int check_arg_const_str(struct bpf_verifier_env *env, struct bpf_reg_state *reg, argno_t argno) { @@ -11947,6 +11954,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ enum bpf_arg_type arg_type = ARG_DONTCARE; argno_t argno = argno_from_arg(i + 1); int regno = reg_from_argno(argno); + bool btf_id_fixed_off_ok = true; u32 ref_id, type_size; bool is_ret_buf_sz = false; int kf_arg_type; @@ -12120,7 +12128,6 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ case KF_ARG_PTR_TO_MEM: case KF_ARG_PTR_TO_MEM_SIZE: case KF_ARG_PTR_TO_CALLBACK: - case KF_ARG_PTR_TO_REFCOUNTED_KPTR: case KF_ARG_PTR_TO_CONST_STR: case KF_ARG_PTR_TO_WORKQUEUE: case KF_ARG_PTR_TO_TIMER: @@ -12134,6 +12141,10 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ case KF_ARG_PTR_TO_CTX: arg_type = ARG_PTR_TO_CTX; break; + case KF_ARG_PTR_TO_REFCOUNTED_KPTR: + arg_type = ARG_PTR_TO_BTF_ID; + btf_id_fixed_off_ok = false; + break; default: verifier_bug(env, "unknown kfunc arg type %d", kf_arg_type); return -EFAULT; @@ -12141,7 +12152,8 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ if (regno == meta->release_regno) arg_type |= OBJ_RELEASE; - ret = check_func_arg_reg_off(env, reg, argno, arg_type); + ret = __check_func_arg_reg_off(env, reg, argno, arg_type, + btf_id_fixed_off_ok); if (ret < 0) return ret; -- cgit v1.2.3 From 72a85e9464a5332fb2cd7efd26d9295275ceda2d Mon Sep 17 00:00:00 2001 From: Nuoqi Gui Date: Tue, 23 Jun 2026 18:43:38 +0800 Subject: bpf: Mask pseudo pointer values in verifier logs print_bpf_insn() masks ldimm64 immediates for pointer-bearing pseudo sources when pointer leaks are not allowed, but the mask only covers BPF_PSEUDO_MAP_FD and BPF_PSEUDO_MAP_VALUE. BPF_PSEUDO_MAP_IDX, BPF_PSEUDO_MAP_IDX_VALUE, and BPF_PSEUDO_BTF_ID can also be resolved to kernel pointer values before the verifier log prints the instruction. Include them in the existing pointer classification so the log prints 0x0 instead of the rewritten address. Fixes: 4976b718c355 ("bpf: Introduce pseudo_btf_id") Fixes: 387544bfa291 ("bpf: Introduce fd_idx") Signed-off-by: Nuoqi Gui Link: https://lore.kernel.org/r/20260623-f01-13-pseudo-btf-id-cap-bpf-v2-1-a190ebb8f3e2@mails.tsinghua.edu.cn Signed-off-by: Alexei Starovoitov Acked-by: Eduard Zingerman --- kernel/bpf/disasm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/disasm.c b/kernel/bpf/disasm.c index f8a3c7eb451e..0391b3bc0073 100644 --- a/kernel/bpf/disasm.c +++ b/kernel/bpf/disasm.c @@ -323,7 +323,10 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs, */ u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; bool is_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD || - insn->src_reg == BPF_PSEUDO_MAP_VALUE; + insn->src_reg == BPF_PSEUDO_MAP_VALUE || + insn->src_reg == BPF_PSEUDO_MAP_IDX || + insn->src_reg == BPF_PSEUDO_MAP_IDX_VALUE || + insn->src_reg == BPF_PSEUDO_BTF_ID; char tmp[64]; if (is_ptr && !allow_ptr_leaks) -- cgit v1.2.3 From 26490a375cb9be9bac96b5171610fd85ca6c2305 Mon Sep 17 00:00:00 2001 From: KaFai Wan Date: Wed, 24 Jun 2026 20:35:35 +0800 Subject: bpf: Fix insn_aux_data leak on verifier err_free_env path When bpf_check() allocates env->insn_aux_data successfully but later fails to allocate env->succ, it jumps directly to err_free_env. The existing vfree(env->insn_aux_data) sits before the err_free_env label, so that direct jump bypasses it and leaks insn_aux_data. Move vfree(env->insn_aux_data) into err_free_env so all early and late exit paths release it consistently. Fixes: 2f69c5685427 ("bpf: make bpf_insn_successors to return a pointer") Signed-off-by: KaFai Wan Reviewed-by: Anton Protopopov Link: https://lore.kernel.org/r/20260624123536.114757-1-kafai.wan@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3cdc2e90f643..6515d4d3c003 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20006,13 +20006,13 @@ err_unlock: if (!is_priv) mutex_unlock(&bpf_verifier_lock); bpf_clear_insn_aux_data(env, 0, env->prog->len); - vfree(env->insn_aux_data); err_free_env: bpf_stack_liveness_free(env); kvfree(env->cfg.insn_postorder); kvfree(env->scc_info); kvfree(env->succ); kvfree(env->gotox_tmp_buf); + vfree(env->insn_aux_data); kvfree(env); return ret; } -- cgit v1.2.3 From 9b51a6155d14389876916726430da30eabb1d4ed Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Fri, 26 Jun 2026 17:52:52 +0200 Subject: bpf,fork: wipe ->bpf_storage before bailouts that access it Currently, copy_process() can bail out to free_task() before p->bpf_storage has been initialized, with this call graph (shown here for the !CONFIG_MEMCG case): copy_process dup_task_struct arch_dup_task_struct [copies the entire task_struct, including ->bpf_storage member] [RLIMIT_NPROC check fails] delayed_free_task free_task bpf_task_storage_free rcu_dereference(task->bpf_storage) bpf_local_storage_destroy In this case, the nascent task's ->bpf_storage member that bpf_local_storage_destroy() operates on is a plain copy of the parent's ->bpf_storage pointer, not a real initialized pointer. This leads to badness (kernel hangs, UAF). This is reachable as long as the process calling fork() has been inserted into a task storage map. Cc: stable@kernel.org Fixes: a10787e6d58c ("bpf: Enable task local storage for tracing programs") Signed-off-by: Jann Horn Signed-off-by: Andrii Nakryiko --- kernel/fork.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index 13e38e89a1f3..f0e2e131a9a5 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1009,6 +1009,11 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node) tsk->mm_cid.active = 0; INIT_HLIST_NODE(&tsk->mm_cid.node); #endif + +#ifdef CONFIG_BPF_SYSCALL + RCU_INIT_POINTER(tsk->bpf_storage, NULL); + tsk->bpf_ctx = NULL; +#endif return tsk; free_stack: @@ -2247,10 +2252,6 @@ __latent_entropy struct task_struct *copy_process( p->sequential_io = 0; p->sequential_io_avg = 0; #endif -#ifdef CONFIG_BPF_SYSCALL - RCU_INIT_POINTER(p->bpf_storage, NULL); - p->bpf_ctx = NULL; -#endif unwind_task_init(p); -- cgit v1.2.3 From a6f0643e4f63cfaa0d5d4a69de4f132eac4b8fe4 Mon Sep 17 00:00:00 2001 From: Matt Bobrowski Date: Sun, 28 Jun 2026 20:11:03 +0000 Subject: bpf: Reject BPF_MAP_TYPE_INODE_STORAGE creation if BPF LSM is uninitialized When CONFIG_BPF_LSM=y is set, BPF inode storage maps (BPF_MAP_TYPE_INODE_STORAGE) are compiled into the kernel. However, if the BPF LSM is not explicitly enabled at boot time (e.g. omitted from the "lsm=" boot parameter), lsm_prepare() is never executed for the BPF LSM. Consequently, the BPF inode security blob offset (bpf_lsm_blob_sizes.lbs_inode) is never initialized and remains at its default compiled size of 8 bytes instead of being updated to a valid offset past the reserved struct rcu_head (typically 16 bytes or more). When a privileged user creates and updates a BPF_MAP_TYPE_INODE_STORAGE map, bpf_inode() evaluates inode->i_security + 8. This erroneously aliases the struct rcu_head.func callback pointer at the beginning of the inode->i_security blob. During subsequent map element cleanup or inode destruction, writing NULL to owner_storage clears the queued RCU callback pointer. When rcu_do_batch() later executes the queued callback, it attempts an instruction fetch at address 0x0, triggering an immediate kernel panic. Fix this by introducing a global bpf_lsm_initialized boolean flag marked with __ro_after_init. Set this flag to true inside bpf_lsm_init() when the LSM framework successfully registers the BPF LSM. Gate map allocation in inode_storage_map_alloc() on this flag, returning -EOPNOTSUPP if the BPF LSM is in turn uninitialized. This fail-fast approach prevents userspace from allocating inode storage maps when the supporting BPF LSM infrastructure is absent, avoiding zombie map states. Fixes: 8ea636848aca ("bpf: Implement bpf_local_storage for inodes") Reported-by: oxsignal Signed-off-by: Matt Bobrowski Signed-off-by: Daniel Borkmann Reviewed-by: Emil Tsalapatis Reviewed-by: Amery Hung Link: https://lore.kernel.org/bpf/20260628201103.3624525-1-mattbobrowski@google.com --- kernel/bpf/bpf_inode_storage.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c index 0da8d923e39d..f9e81060c1f4 100644 --- a/kernel/bpf/bpf_inode_storage.c +++ b/kernel/bpf/bpf_inode_storage.c @@ -178,6 +178,15 @@ static int notsupp_get_next_key(struct bpf_map *map, void *key, static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr) { + /* + * Do not allow allocation of BPF_MAP_TYPE_INODE_STORAGE if the BPF LSM + * was not initialized by the LSM framework at boot. Without proper + * initialization, the BPF inode security blob offset remains unprepared, + * causing bpf_inode() to calculate an invalid memory offset and corrupt + * inode->i_security. + */ + if (!bpf_lsm_initialized) + return ERR_PTR(-EOPNOTSUPP); return bpf_local_storage_map_alloc(attr, &inode_cache); } -- cgit v1.2.3 From 251a8fe1b9aedccd298b77bc28426d564c5a923f Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Thu, 25 Jun 2026 08:34:46 +0900 Subject: tracing/probes: Remove WARN_ON_ONCE from parse_btf_arg Sashiko found that user can cause this WARN_ON_ONCE() easily with adding a kprobe event based on a raw address with BTF parameter. Since this is not an unexpected condition, remove the WARN_ON_ONCE(). Link: https://lore.kernel.org/all/178177265367.2059927.13789953014706792126.stgit@mhiramat.tok.corp.google.com/ Link: https://sashiko.dev/#/patchset/178165816303.269421.7302603996990753309.stgit%40devnote2 Reported-by: Sashiko Fixes: b576e09701c7 ("tracing/probes: Support function parameters if BTF is available") Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_probe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index fd1caa1f9723..98532c503d02 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -678,7 +678,7 @@ static int parse_btf_arg(char *varname, int i, is_ptr, ret; u32 tid; - if (WARN_ON_ONCE(!ctx->funcname && !(ctx->flags & TPARG_FL_TEVENT))) + if (!ctx->funcname && !(ctx->flags & TPARG_FL_TEVENT)) return -EINVAL; is_ptr = split_next_field(varname, &field, ctx); -- cgit v1.2.3 From 206b25c09080cc20fd4c2bea12d59df4b7ba2121 Mon Sep 17 00:00:00 2001 From: Martin Kaiser Date: Thu, 25 Jun 2026 08:34:46 +0900 Subject: tracing: eprobe: read the complete FILTER_PTR_STRING pointer For a char * element in an event, the FILTER_PTR_STRING filter type is used. When the event occurs, a pointer is stored in the ringbuffer. If an eprobe references such a char * element of a "base event", the stored pointer is truncated when it's read from the ringbuffer. $ cd /sys/kernel/tracing $ echo 'e rcu.rcu_utilization $s:x64 $s:string' > dynamic_events $ echo 1 > tracing_on $ echo 1 > events/eprobes/enable $ sleep 1 $ echo 0 > events/eprobes/enable $ cat trace -0 ...: (rcu.rcu_utilization) arg1=0x4f arg2=(fault) -0 ...: (rcu.rcu_utilization) arg1=0x2 arg2=(fault) The problem is in get_event_field val = (unsigned long)(*(char *)addr); addr points to the position in the ringbuffer where the pointer was stored. The assignment reads only the lowest byte of the pointer. Fix the cast to read the whole pointer. The output of the test above is now -0 ... arg1=0xffffffff81c7d3f3 arg2="Start scheduler-tick" -0 ... arg1=0xffffffff81c57340 arg2="End scheduler-tick" Link: https://lore.kernel.org/all/20260620145339.3234726-1-martin@kaiser.cx/ Fixes: f04dec93466a ("tracing/eprobes: Fix reading of string fields") Signed-off-by: Martin Kaiser Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_eprobe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c index b66d6196338d..50518b071414 100644 --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -315,7 +315,7 @@ get_event_field(struct fetch_insn *code, void *rec) val = (unsigned long)addr; break; case FILTER_PTR_STRING: - val = (unsigned long)(*(char *)addr); + val = *(unsigned long *)addr; break; default: WARN_ON_ONCE(1); -- cgit v1.2.3 From 9a667b7750dda88cbf1cca96a53a2163b2ee71f7 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Thu, 25 Jun 2026 08:34:47 +0900 Subject: tracing/probes: Fix double addition of offset for @+FOFFSET Since commit 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code") wrongly use @offset local variable during the parsing, the offset value is added twice when dereferencing. Reset the @offset after setting it in FETCH_OP_FOFFS. Link: https://lore.kernel.org/all/178217905962.643090.1978577464942171332.stgit@devnote2/ Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code") Signed-off-by: Masami Hiramatsu (Google) Cc: stable@vger.kernel.org --- kernel/trace/trace_probe.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 98532c503d02..502fa6da5949 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -1241,6 +1241,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type, code->op = FETCH_OP_FOFFS; code->immediate = (unsigned long)offset; // imm64? + offset = 0; } else { /* uprobes don't support symbols */ if (!(ctx->flags & TPARG_FL_KERNEL)) { -- cgit v1.2.3 From 367c49d6e283c17b56a31e7a8d964a079244264c Mon Sep 17 00:00:00 2001 From: Sechang Lim Date: Thu, 25 Jun 2026 08:34:48 +0900 Subject: tracing/fprobe: Fix NULL pointer dereference in fprobe_fgraph_entry() fprobe_fgraph_entry() sizes a shadow-stack reservation in one walk of the per-ip fprobe list and fills it in a second walk, both under rcu_read_lock() only. A fprobe registered on an already-live ip can become visible between the two walks, so the fill walk processes an exit_handler the sizing walk did not count and used runs past reserved_words. If the sizing walk counted nothing, fgraph_data is NULL and the first write_fprobe_header() faults: Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:fprobe_fgraph_entry+0xa38/0xf10 kernel/trace/fprobe.c:167 Call Trace: function_graph_enter_regs+0x44c/0xa10 kernel/trace/fgraph.c:677 ftrace_graph_func+0xc5/0x140 arch/x86/kernel/ftrace.c:671 __kernel_text_address+0x9/0x40 kernel/extable.c:78 arch_stack_walk+0x117/0x170 arch/x86/kernel/stacktrace.c:26 kmem_cache_free+0x188/0x580 mm/slub.c:6378 tcp_data_queue+0x18d/0x6550 net/ipv4/tcp_input.c:5590 [...] The list cannot be frozen across the two walks, so skip a node that does not fit the reservation and count it as missed. Link: https://lore.kernel.org/all/20260619184425.3824774-1-rhkrqnwk98@gmail.com/ Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer") Signed-off-by: Sechang Lim Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/fprobe.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index f378613ad120..f215990b9061 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -613,6 +613,16 @@ static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops continue; data_size = fp->entry_data_size; + /* + * The list may have grown since it was sized, so this node + * may not fit. Skip it as missed rather than overrun the + * reservation. + */ + if (fp->exit_handler && + used + FPROBE_HEADER_SIZE_IN_LONG + SIZE_IN_LONG(data_size) > reserved_words) { + fp->nmissed++; + continue; + } if (data_size && fp->exit_handler) data = fgraph_data + used + FPROBE_HEADER_SIZE_IN_LONG; else -- cgit v1.2.3 From a369299c3f785cf556bbef2de2db0aa2d294c4c9 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Thu, 25 Jun 2026 08:34:48 +0900 Subject: tracing/probes: Make the $ prefix mandatory for comm access Since $comm or $COMM are not event field but special fetcharg variables to access current->comm, It should not be accessed without '$' prefix even with typecast. Link: https://lore.kernel.org/all/178231209724.732967.12049805699091810641.stgit@devnote2/ Fixes: 69efd863a785 ("tracing/eprobes: Allow use of BTF names to dereference pointers") Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_probe.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 502fa6da5949..d17cfee77d9c 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -342,10 +342,6 @@ static int parse_trace_event(char *arg, struct fetch_insn *code, ret = parse_trace_event_arg(arg, code, ctx); if (!ret) return 0; - if (strcmp(arg, "comm") == 0 || strcmp(arg, "COMM") == 0) { - code->op = FETCH_OP_COMM; - return 0; - } return -EINVAL; } @@ -1068,8 +1064,14 @@ static int parse_probe_vars(char *orig_arg, const struct fetch_type *t, int len; if (ctx->flags & TPARG_FL_TEVENT) { - if (parse_trace_event(arg, code, ctx) < 0) + if (parse_trace_event(arg, code, ctx) < 0) { + /* 'comm' should be checked after field parsing. */ + if (strcmp(arg, "comm") == 0 || strcmp(arg, "COMM") == 0) { + code->op = FETCH_OP_COMM; + return 0; + } goto inval; + } return 0; } -- cgit v1.2.3 From c9a71daaecb2fb1d8c704545cc0b1c920b9bf5d7 Mon Sep 17 00:00:00 2001 From: Chi Wang Date: Fri, 19 Jun 2026 15:42:44 +0800 Subject: audit: Fix data races of skb_queue_len() readers on audit_queue MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Multiple readers access audit_queue.qlen via skb_queue_len() without holding the queue lock or using READ_ONCE(), while kauditd writes to this field via the skb_dequeue() → __skb_unlink() path with WRITE_ONCE() protected by a spinlock. This constitutes data races. All affected skb_queue_len(&audit_queue) call sites: - kauditd_thread() wait_event_freezable() condition - audit_receive_msg() AUDIT_GET handler (s.backlog assignment) - audit_receive() backlog check - audit_log_start() backlog check and pr_warn() KCSAN reports the following conflicting access pattern (one example): ================================================================== BUG: KCSAN: data-race in audit_log_start / skb_dequeue write (marked) to 0xffffffff8512ee20 of 4 bytes by task 661 on cpu 57: skb_dequeue+0x70/0xf0 kauditd_send_queue+0x71/0x220 kauditd_thread+0x1cb/0x430 kthread+0x1c2/0x210 ret_from_fork+0x162/0x1a0 ret_from_fork_asm+0x1a/0x30 read to 0xffffffff8512ee20 of 4 bytes by task 36586 on cpu 1: audit_log_start+0x2a0/0x6b0 audit_core_dumps+0x64/0xa0 do_coredump+0x14b/0x1260 get_signal+0xeb2/0xf70 arch_do_signal_or_restart+0x41/0x170 exit_to_user_mode_loop+0xa2/0x1c0 do_syscall_64+0x1a3/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0xe0 value changed: 0x00000001 -> 0x00000000 ================================================================== Resolve the race by switching to lockless helper skb_queue_len_lockless(), which internally uses READ_ONCE() and properly pairs with the WRITE_ONCE() write accesses already present on the writer side. Cc: stable@vger.kernel.org Fixes: 3197542482df ("audit: rework audit_log_start()") Signed-off-by: Chi Wang Reviewed-by: Ricardo Robaina [PM: line length tweak] Signed-off-by: Paul Moore --- kernel/audit.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/audit.c b/kernel/audit.c index dcc657d35776..feaa4e2271d7 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -950,7 +950,7 @@ main_queue: * do the multicast send and rotate records from the * main queue to the retry/hold queues */ wait_event_freezable(kauditd_wait, - (skb_queue_len(&audit_queue) ? 1 : 0)); + (skb_queue_len_lockless(&audit_queue) ? 1 : 0)); } return 0; @@ -1283,7 +1283,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh, s.rate_limit = audit_rate_limit; s.backlog_limit = audit_backlog_limit; s.lost = atomic_read(&audit_lost); - s.backlog = skb_queue_len(&audit_queue); + s.backlog = skb_queue_len_lockless(&audit_queue); s.feature_bitmap = AUDIT_FEATURE_BITMAP_ALL; s.backlog_wait_time = audit_backlog_wait_time; s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual); @@ -1627,7 +1627,7 @@ static void audit_receive(struct sk_buff *skb) /* can't block with the ctrl lock, so penalize the sender now */ if (audit_backlog_limit && - (skb_queue_len(&audit_queue) > audit_backlog_limit)) { + (skb_queue_len_lockless(&audit_queue) > audit_backlog_limit)) { DECLARE_WAITQUEUE(wait, current); /* wake kauditd to try and flush the queue */ @@ -1933,7 +1933,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, long stime = audit_backlog_wait_time; while (audit_backlog_limit && - (skb_queue_len(&audit_queue) > audit_backlog_limit)) { + (skb_queue_len_lockless(&audit_queue) > audit_backlog_limit)) { /* wake kauditd to try and flush the queue */ wake_up_interruptible(&kauditd_wait); @@ -1953,7 +1953,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, } else { if (audit_rate_check() && printk_ratelimit()) pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n", - skb_queue_len(&audit_queue), + skb_queue_len_lockless(&audit_queue), audit_backlog_limit); audit_log_lost("backlog limit exceeded"); return NULL; -- cgit v1.2.3 From 96cce16e26dd02a8678f1e87f88a4b5cdb63b995 Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Mon, 29 Jun 2026 22:37:52 -0700 Subject: bpf: Support for hardening against JIT spraying The BPF JIT allocator packs many small programs into larger executable allocations and reuses space within those allocations as programs are loaded and freed. When fresh code is written into space that a previous program occupied, an indirect jump into the new program can reuse a branch prediction left behind by the old one. Flush the indirect branch predictors before reusing JIT memory so that indirect jumps into a newly written program don't reuse predictions from an old program that occupied the same space. Introduce bpf_arch_pred_flush_enabled static key and bpf_arch_pred_flush static call for flushing the branch predictors on JIT memory reuse. Architectures that need a flush, can update it to a predictor flush function. By default, its a NOP and does not emit any CALL. Allocations larger than a pack are not covered by this flush. That is safe because cBPF programs (the unprivileged attack surface) are bounded well below a pack size. Issue a warning if this assumption is ever violated while the flush is active. Signed-off-by: Pawan Gupta Acked-by: Daniel Borkmann Signed-off-by: Daniel Borkmann --- kernel/bpf/core.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 649cce41e13f..7f0a17f128d4 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -883,6 +884,15 @@ void bpf_jit_fill_hole_with_zero(void *area, unsigned int size) memset(area, 0, size); } +DEFINE_STATIC_CALL_NULL(bpf_arch_pred_flush, bpf_arch_pred_flush); + +/* + * Enabled once bpf_arch_pred_flush points at a real flush routine. Lets the + * pack allocator test "is a predictor flush wired up at all" with a cheap + * static branch instead of repeatedly querying the static call target. + */ +DEFINE_STATIC_KEY_FALSE(bpf_pred_flush_enabled); + #define BPF_PROG_SIZE_TO_NBITS(size) (round_up(size, BPF_PROG_CHUNK_SIZE) / BPF_PROG_CHUNK_SIZE) static DEFINE_MUTEX(pack_mutex); @@ -941,6 +951,14 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) mutex_lock(&pack_mutex); if (size > BPF_PROG_PACK_SIZE) { + /* + * Allocations larger than a pack get their own pages, and + * predictors are not flushed for such allocation. This is only + * safe because cBPF programs (the unprivileged attack surface) + * are bounded well below a pack size. + */ + if (static_branch_unlikely(&bpf_pred_flush_enabled)) + pr_warn_once("BPF: Predictors not flushed for allocations greater than BPF_PROG_PACK_SIZE\n"); size = round_up(size, PAGE_SIZE); ptr = bpf_jit_alloc_exec(size); if (ptr) { @@ -971,6 +989,7 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) pos = 0; found_free_area: + static_call_cond(bpf_arch_pred_flush)(); bitmap_set(pack->bitmap, pos, nbits); ptr = (void *)(pack->ptr) + (pos << BPF_PROG_CHUNK_SHIFT); -- cgit v1.2.3 From 0bb99f2cfaae6822d734d69722de30af823efdf3 Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Mon, 29 Jun 2026 22:38:23 -0700 Subject: bpf: Restrict JIT predictor flush to cBPF Currently predictor flush on memory reuse is done for all BPF JIT allocations, but only cBPF programs can be loaded by an unprivileged user. eBPF is privileged by default, and flushing predictors for all CPUs on every eBPF reuse penalizes the common case for no security benefit. eBPF allocations can be frequent on busy systems, only flush predictors for cBPF programs. Trampoline and dispatcher allocations also skip the flush as they are eBPF-only. Signed-off-by: Pawan Gupta Acked-by: Daniel Borkmann Signed-off-by: Daniel Borkmann --- kernel/bpf/core.c | 13 ++++++++----- kernel/bpf/dispatcher.c | 2 +- 2 files changed, 9 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 7f0a17f128d4..1614ccc3f111 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -942,7 +942,7 @@ out: return NULL; } -void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) +void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns, bool was_classic) { unsigned int nbits = BPF_PROG_SIZE_TO_NBITS(size); struct bpf_prog_pack *pack; @@ -957,7 +957,7 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) * safe because cBPF programs (the unprivileged attack surface) * are bounded well below a pack size. */ - if (static_branch_unlikely(&bpf_pred_flush_enabled)) + if (was_classic && static_branch_unlikely(&bpf_pred_flush_enabled)) pr_warn_once("BPF: Predictors not flushed for allocations greater than BPF_PROG_PACK_SIZE\n"); size = round_up(size, PAGE_SIZE); ptr = bpf_jit_alloc_exec(size); @@ -989,7 +989,9 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns) pos = 0; found_free_area: - static_call_cond(bpf_arch_pred_flush)(); + /* Flush only for cBPF as it may contain a crafted gadget */ + if (static_branch_unlikely(&bpf_pred_flush_enabled) && was_classic) + static_call_cond(bpf_arch_pred_flush)(); bitmap_set(pack->bitmap, pos, nbits); ptr = (void *)(pack->ptr) + (pos << BPF_PROG_CHUNK_SHIFT); @@ -1149,7 +1151,8 @@ bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **image_ptr, unsigned int alignment, struct bpf_binary_header **rw_header, u8 **rw_image, - bpf_jit_fill_hole_t bpf_fill_ill_insns) + bpf_jit_fill_hole_t bpf_fill_ill_insns, + bool was_classic) { struct bpf_binary_header *ro_header; u32 size, hole, start; @@ -1162,7 +1165,7 @@ bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **image_ptr, if (bpf_jit_charge_modmem(size)) return NULL; - ro_header = bpf_prog_pack_alloc(size, bpf_fill_ill_insns); + ro_header = bpf_prog_pack_alloc(size, bpf_fill_ill_insns, was_classic); if (!ro_header) { bpf_jit_uncharge_modmem(size); return NULL; diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c index b77db7413f8c..ea2d60dc1fee 100644 --- a/kernel/bpf/dispatcher.c +++ b/kernel/bpf/dispatcher.c @@ -145,7 +145,7 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, mutex_lock(&d->mutex); if (!d->image) { - d->image = bpf_prog_pack_alloc(PAGE_SIZE, bpf_jit_fill_hole_with_zero); + d->image = bpf_prog_pack_alloc(PAGE_SIZE, bpf_jit_fill_hole_with_zero, false); if (!d->image) goto out; d->rw_image = bpf_jit_alloc_exec(PAGE_SIZE); -- cgit v1.2.3 From a23c1c5396a91680703360d1ee28a44657c503c4 Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Mon, 29 Jun 2026 22:38:38 -0700 Subject: bpf: Skip redundant IBPB in pack allocator bpf_prog_pack_alloc() issues IBPB on all CPUs on every cBPF allocation, even when reusing chunks from an existing pack where no new memory was touched since the last IBPB. Since IBPB on all CPUs is heavy, Dave Hansen suggested to track allocation since last IBPB, and only issue IBPB at reuse for the chunks that have not seen an IBPB since they were last freed. Track per-pack whether an IBPB is needed via arch_flush_needed. Set it when allocating a chunk, reset on IBPB flush. On reuse, conditionally issue the flush. Since IBPB invalidates all BTB entries, clear the flag on all packs after flushing. Signed-off-by: Pawan Gupta Acked-by: Daniel Borkmann Signed-off-by: Daniel Borkmann --- kernel/bpf/core.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 1614ccc3f111..50aba113ef9d 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -876,6 +876,7 @@ int bpf_jit_add_poke_descriptor(struct bpf_prog *prog, struct bpf_prog_pack { struct list_head list; void *ptr; + bool arch_flush_needed; unsigned long bitmap[]; }; @@ -928,6 +929,8 @@ static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_ins bpf_fill_ill_insns(pack->ptr, BPF_PROG_PACK_SIZE); bitmap_zero(pack->bitmap, BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE); + if (static_branch_unlikely(&bpf_pred_flush_enabled)) + pack->arch_flush_needed = true; set_vm_flush_reset_perms(pack->ptr); err = set_memory_rox((unsigned long)pack->ptr, BPF_PROG_PACK_SIZE / PAGE_SIZE); @@ -990,8 +993,15 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns, bool found_free_area: /* Flush only for cBPF as it may contain a crafted gadget */ - if (static_branch_unlikely(&bpf_pred_flush_enabled) && was_classic) + if (static_branch_unlikely(&bpf_pred_flush_enabled) && + pack->arch_flush_needed && + was_classic) { + struct bpf_prog_pack *p; + static_call_cond(bpf_arch_pred_flush)(); + list_for_each_entry(p, &pack_list, list) + p->arch_flush_needed = false; + } bitmap_set(pack->bitmap, pos, nbits); ptr = (void *)(pack->ptr) + (pos << BPF_PROG_CHUNK_SHIFT); @@ -1029,6 +1039,9 @@ void bpf_prog_pack_free(void *ptr, u32 size) "bpf_prog_pack bug: missing bpf_arch_text_invalidate?\n"); bitmap_clear(pack->bitmap, pos, nbits); + + if (static_branch_unlikely(&bpf_pred_flush_enabled)) + pack->arch_flush_needed = true; if (bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0, BPF_PROG_CHUNK_COUNT, 0) == 0) { list_del(&pack->list); -- cgit v1.2.3 From a9b1f19a6a673ba06820898d0f1ad02883ea1639 Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Mon, 29 Jun 2026 22:38:54 -0700 Subject: bpf: Prefer packs that won't trigger an IBPB flush on allocation Currently BPF pack allocator picks the chunks from the first available pack. While this is okay, it naturally leads to more frequent flushes when there are multiple packs in the system that weren't used since the last flush. As an optimization prefer allocating the new programs from packs that are unused since last flush. When all packs are dirty, allocation forces a flush and marks all packs clean. Below are some future optimizations ideas: 1. Currently, the "dirty" tracking is only done at the pack-level. Flush frequency can further be reduced with chunk-level tracking. This requires a new bitmap per-pack to track the dirty state. 2. IBPB flush is done on all CPUs, even if only a single CPU ran the BPF program. On a system with hundreds of CPUs this could be a major bottleneck forcing hundreds of IPIs to deliver the flush. The solution is to track the CPUs where a BPF program ran, and issue IBPB only on those CPUs. 3. Avoid IBPB when flush is already done at other sources (e.g. context switch). Signed-off-by: Pawan Gupta Acked-by: Daniel Borkmann Signed-off-by: Daniel Borkmann --- kernel/bpf/core.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 50aba113ef9d..1b32b9f2491f 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -948,8 +948,8 @@ out: void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns, bool was_classic) { unsigned int nbits = BPF_PROG_SIZE_TO_NBITS(size); - struct bpf_prog_pack *pack; - unsigned long pos; + struct bpf_prog_pack *pack, *fallback_pack = NULL; + unsigned long pos, fallback_pos = 0; void *ptr = NULL; mutex_lock(&pack_mutex); @@ -981,8 +981,29 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns, bool list_for_each_entry(pack, &pack_list, list) { pos = bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0, nbits, 0); - if (pos < BPF_PROG_CHUNK_COUNT) + if (pos >= BPF_PROG_CHUNK_COUNT) + continue; + /* Flush not enabled, use any pack */ + if (!static_branch_unlikely(&bpf_pred_flush_enabled)) goto found_free_area; + /* + * cBPF reuse of a dirty pack triggers a flush, so prefer a + * clean pack for cBPF. eBPF never flushes, so pick the first + * free pack, dirty or clean. + */ + if (!was_classic || !pack->arch_flush_needed) + goto found_free_area; + if (!fallback_pack) { + fallback_pack = pack; + fallback_pos = pos; + } + } + + /* No preferred pack found */ + if (fallback_pack) { + pack = fallback_pack; + pos = fallback_pos; + goto found_free_area; } pack = alloc_new_pack(bpf_fill_ill_insns); -- cgit v1.2.3 From b72e29e0f7ee329d89f86db8700c8ea99b4a370a Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Mon, 29 Jun 2026 22:39:29 -0700 Subject: bpf: Prefer dirty packs for eBPF allocations The pack allocator only flushes predictors when reusing a dirty pack for cBPF, eBPF allocations never trigger a flush. Currently, eBPF picks the first free pack, which could be a clean pack. As an optimization, leaving a clean pack for cBPF can avoid flushes. Prefer dirty packs for eBPF and keep clean packs free for cBPF. This mirrors the existing cBPF preference for clean packs: each program kind prefers the pack that avoids an extra flush, and falls back to the other kind only when no preferred pack has room. eBPF reuse of a dirty pack is harmless since eBPF being privileged does not flush. Signed-off-by: Pawan Gupta Acked-by: Daniel Borkmann Signed-off-by: Daniel Borkmann --- kernel/bpf/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 1b32b9f2491f..6e19a030da6f 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -988,10 +988,10 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns, bool goto found_free_area; /* * cBPF reuse of a dirty pack triggers a flush, so prefer a - * clean pack for cBPF. eBPF never flushes, so pick the first - * free pack, dirty or clean. + * clean pack for cBPF. eBPF never flushes, so steer it to a + * dirty pack and keep clean packs free for cBPF. */ - if (!was_classic || !pack->arch_flush_needed) + if (was_classic ^ pack->arch_flush_needed) goto found_free_area; if (!fallback_pack) { fallback_pack = pack; -- cgit v1.2.3 From 037a3c43edfb597665dd34457cd22b14692f2ba3 Mon Sep 17 00:00:00 2001 From: Taeyang Lee <0wn@theori.io> Date: Sun, 14 Jun 2026 23:22:18 +0900 Subject: perf/core: Detach event groups during remove_on_exec perf_event_remove_on_exec() removes events by calling perf_event_exit_event(). For top-level events, this removes the event from the context with DETACH_EXIT only. This can leave inconsistent group state when a removed event is a group leader and the group contains siblings without remove_on_exec. If the group was active, the surviving siblings can remain active and attached to the removed leader's sibling list, but are no longer represented by a valid group leader on the PMU context active lists. A later close of the removed leader uses DETACH_GROUP and can promote the still-active siblings from this stale group state. The next schedule-in can then add an already-linked active_list entry again, corrupting the PMU context active list. With DEBUG_LIST enabled, this is caught as a list_add double-add in merge_sched_in(). Fix this by detaching group relationships when remove_on_exec removes an event. This preserves the existing task-exit and revoke behavior, while ensuring surviving siblings are ungrouped before the removed event leaves the context. Fixes: 2e498d0a74e5 ("perf: Add support for event removal on exec") Signed-off-by: Taeyang Lee <0wn@theori.io> Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/ai65GgZcC0LAlWLG@Taeyangs-MacBook-Pro.local --- kernel/events/core.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 954c36e28101..d7f3e2c2ecb1 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4729,7 +4729,7 @@ static void perf_remove_from_owner(struct perf_event *event); static void perf_event_exit_event(struct perf_event *event, struct perf_event_context *ctx, struct task_struct *task, - bool revoke); + unsigned long detach_flags); /* * Removes all events from the current task that have been marked @@ -4756,7 +4756,7 @@ static void perf_event_remove_on_exec(struct perf_event_context *ctx) modified = true; - perf_event_exit_event(event, ctx, ctx->task, false); + perf_event_exit_event(event, ctx, ctx->task, DETACH_GROUP); } raw_spin_lock_irqsave(&ctx->lock, flags); @@ -12937,7 +12937,7 @@ static void __pmu_detach_event(struct pmu *pmu, struct perf_event *event, /* * De-schedule the event and mark it REVOKED. */ - perf_event_exit_event(event, ctx, ctx->task, true); + perf_event_exit_event(event, ctx, ctx->task, DETACH_REVOKE); /* * All _free_event() bits that rely on event->pmu: @@ -14525,12 +14525,13 @@ static void perf_event_exit_event(struct perf_event *event, struct perf_event_context *ctx, struct task_struct *task, - bool revoke) + unsigned long detach_flags) { struct perf_event *parent_event = event->parent; - unsigned long detach_flags = DETACH_EXIT; unsigned int attach_state; + detach_flags |= DETACH_EXIT; + if (parent_event) { /* * Do not destroy the 'original' grouping; because of the @@ -14553,8 +14554,8 @@ perf_event_exit_event(struct perf_event *event, sync_child_event(event, task); } - if (revoke) - detach_flags |= DETACH_GROUP | DETACH_REVOKE; + if (detach_flags & DETACH_REVOKE) + detach_flags |= DETACH_GROUP; perf_remove_from_context(event, detach_flags); /* @@ -14642,7 +14643,7 @@ static void perf_event_exit_task_context(struct task_struct *task, bool exit) perf_event_task(task, ctx, 0); list_for_each_entry_safe(child_event, next, &ctx->event_list, event_entry) - perf_event_exit_event(child_event, ctx, exit ? task : NULL, false); + perf_event_exit_event(child_event, ctx, exit ? task : NULL, 0); mutex_unlock(&ctx->mutex); -- cgit v1.2.3 From 39def6d250d370298f86c116f4ac60093cefadaa Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 1 Jul 2026 15:11:50 +0200 Subject: futex/requeue: Revert "Prevent NULL pointer dereference in remove_waiter() on self-deadlock"" The commit cited below should not have been merged. It attemted to fix an existing problem ansd thereby introduced new problems by keeping the pi_state in state Q_REQUEUE_PI_IN_PROGRESS and leaking it. Based on the commit description the intention was to handle the case when task_blocks_on_rt_mutex() returns -EDEADLK and the following remove_waiter() dereferences the NULL pointer in waiter->task. That is already handled by Davidlohr in commit 40a25d59e85b3 ("locking/rtmutex: Skip remove_waiter() when waiter is not enqueued") and requires no further acting. Revert the commit breaking the "waiter == owner" case again. Fixes: 74e144274af39 ("futex/requeue: Prevent NULL pointer dereference in remove_waiter() on self-deadlock") Reported-by: Michael Bommarito Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260701131150.0Ijhq4Dw@linutronix.de Closes: https://lore.kernel.org/all/20260629020049.2082397-1-michael.bommarito@gmail.com --- kernel/futex/requeue.c | 6 ------ 1 file changed, 6 deletions(-) (limited to 'kernel') diff --git a/kernel/futex/requeue.c b/kernel/futex/requeue.c index 7384672916fb..79823ad13683 100644 --- a/kernel/futex/requeue.c +++ b/kernel/futex/requeue.c @@ -645,12 +645,6 @@ retry_private: continue; } - /* Self-deadlock: non-top waiter already owns the PI futex. */ - if (rt_mutex_owner(&pi_state->pi_mutex) == this->task) { - ret = -EDEADLK; - break; - } - ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex, this->rt_waiter, this->task); -- cgit v1.2.3 From 920f893f735e92ba3a1cd9256899a186b161928d Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 3 Jul 2026 12:02:38 +0200 Subject: posix-cpu-timers: Prevent UAF caused by non-leader exec() race Wongi and Jungwoo decoded and reported a non-leader exec() related race which can result in an UAF: sys_timer_delete() exec() posix_cpu_timer_del() // Observes old leader p = pid_task(pid, pid_type); de_thread() switch_leader(); release_task(old_leader) __exit_signal(old_leader) sighand = lock(old_leader, sighand); posix_cpu_timers*_exit(); sighand = lock_task_sighand(p) unhash_task(old_leader); sh = lock(p, sighand) old_leader->sighand = NULL; unlock(sighand); (p->sighand == NULL) unlock(sh) return NULL; // Returns without action if(!sighand) return 0; free_posix_timer(); This is "harmless" unless the deleted timer was armed and enqueued in p->signal because on exec() a TGID targeted timer is inherited. As sys_timer_delete() freed the underlying posix timer object run_posix_cpu_timers() or any timerqueue related add/delete operations on other timers will access the freed object's timerqueue node, which results in an UAF. There is a similar problem vs. posix_cpu_timer_set(). For regular posix timers it just transiently returns -ESRCH to user space, but for the use case in do_cpu_nanosleep() it's the same UAF just that the k_itimer is allocated on the stack. Also posix_cpu_timer_rearm() fails to rearm the timer, which means it stops to expire. While debating solutions Frederic pointed out another problem: posix_cpu_timer_del(tmr) __exit_signal(p) posix_cpu_timers*_exit(p); unhash_task(p); p->sighand = NULL; sh = lock_task_sighand(p) sighand = p->sighand; if (!sighand) return NULL; lock(sighand); if (!sh) WARN_ON_ONCE(timer_queued(tmr)); On weakly ordered architectures it is not guaranteed that posix_cpu_timer_del() will observe the stores in posix_cpu_timers*_exit() when p->sighand is observed as NULL, which means the WARN() can be a false positive. Solve these issues by: 1) Changing the store in __exit_signal() to smp_store_release(). 2) Adding a smp_acquire__after_ctrl_dep() into the !sighand path of lock_task_sighand(). 3) Creating a helper function for looking up the task and locking sighand which does not return when sighand == NULL. Instead it retries the task lookup and only if that fails it gives up. 4) Using that helper in the three affected functions. #1/#2 ensures that the reader side which observes sighand == NULL also observes all preceeding stores, i.e. the stores in posix_cpu_timers*_exit() and the ones in unhash_task(). #3 ensures that the above described non-leader exec() situation is handled gracefully. When the task lookup returns the old leader, but sighand == NULL then it retries. In the non-leader exec() case the subsequent task lookup will observe the new leader due to #1/#2. In normal exit() scenarios the subsequent lookup fails. When the task lookup fails, the function also checks whether the timer is still enqueued and issues a warning if that's the case. Unfortunately there is nothing which can be done about it, but as the task is already not longer visible the timer should not be accessed anymore. This check also requires memory ordering, which is not provided when the first lookup fails. To achieve that the check is preceeded by a smp_rmb() which pairs with the smp_wmb() in write_seqlock() in __exit_signal(). That ensures that the stores in posix_cpu_timers*_exit() are visible. The history of the non-leader exec() issue goes back to the early days of posix CPU timers, which stored a pointer to the group leader task in the timer. That obviously fails when a non-leader exec() switches the leader. commit e0a70217107e ("posix-cpu-timers: workaround to suppress the problems with mt exec") added a temporary workaround for that in 2010 which survived about 10 years. The fix for the workaround changed the task pointer to a pid pointer, but failed to see the subtle race described above. So the Fixes tag picks that commit, which seems to be halfways accurate. Thanks to Frederic Weissbecker, Oleg Nesterov and Peter Zijlstra for review, feedback and suggestions and to Wongi and Jungwoo for the excellent bug report and analysis! Fixes: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task") Reported-by: Wongi Lee Reported-by: Jungwoo Lee Signed-off-by: Thomas Gleixner Reviewed-by: Oleg Nesterov Cc: stable@vger.kernel.org --- kernel/exit.c | 7 +- kernel/signal.c | 10 ++- kernel/time/posix-cpu-timers.c | 173 +++++++++++++++++++++++++++-------------- 3 files changed, 130 insertions(+), 60 deletions(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index 1056422bc101..2c0b1c02920f 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -212,7 +212,12 @@ static void __exit_signal(struct release_task_post *post, struct task_struct *ts __unhash_process(post, tsk, group_dead); write_sequnlock(&sig->stats_lock); - tsk->sighand = NULL; + /* + * Ensure that all preceeding state is visible. Pairs with + * the smp_acquire__after_ctrl_dep() in the sighand == NULL + * path of lock_task_sighand(). + */ + smp_store_release(&tsk->sighand, NULL); spin_unlock(&sighand->siglock); __cleanup_sighand(sighand); diff --git a/kernel/signal.c b/kernel/signal.c index 9c2b32c4d755..bbc0fd4cc4d7 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1362,8 +1362,16 @@ struct sighand_struct *lock_task_sighand(struct task_struct *tsk, rcu_read_lock(); for (;;) { sighand = rcu_dereference(tsk->sighand); - if (unlikely(sighand == NULL)) + if (unlikely(sighand == NULL)) { + /* + * Pairs with the smp_store_release() in + * __exit_signal(). It ensures that all state + * modifications to the task preceeding the store are + * visible to the callers of lock_task_sighand(). + */ + smp_acquire__after_ctrl_dep(); break; + } /* * This sighand can be already freed and even reused, but diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 5e633d8750d1..a7d3e8229c4b 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -461,6 +461,109 @@ static void disarm_timer(struct k_itimer *timer, struct task_struct *p) trigger_base_recalc_expires(timer, p); } +/* + * Lookup the task via timer->it.cpu.pid and attempt to lock the task's sighand. + * + * This can race with the reaping of the task: + * + * CPU0 CPU1 + * + * // Finds task + * p = pid_task(pid, pid_type); __exit_signal(p) + * lock(p, sighand); + * posix_cpu_timers*_exit(); + * sighand = lock_task_sighand(p); unhash_task(p); + * p->sighand = NULL; + * unlock(sighand); + * + * In this case sighand is NULL, which means the task and the associated timer + * queue cannot be longer accessed safely. + * + * __exit_signal() invokes posix_cpu_timers_exit() and if the thread group is + * dead it also invokes posix_cpu_timers_group_exit(). These functions delete + * all pending timers from the related timer queues. The POSIX timers (k_itimer) + * themself are still accessible, but not longer connected to the task. + * + * exec() works slightly differently. The task which exec()'s terminates all + * other threads in the thread group and runs __exit_signal() on them. As the + * thread group is not dead they only clean up the per task timers via + * posix_cpu_timers_exit(). + * + * As the TGID on exec() stays the same per process timers stay queued, if they + * are armed. This works without a problem when exec() is done by the thread + * group leader. If a non-leader thread exec()'s this can end up in the + * following scenario: + * + * CPU0 CPU1 + * // Returns old leader + * p = pid_task(pid, pid_type); de_thread() + * switch_leader() + * release_task(old leader) + * __exit_signal() + * old_leader->sighand = NULL; + * // Returns NULL + * sighand = lock_task_sighand(p) + * + * That's problematic for several functions: + * + * - posix_cpu_timer_del(): If the timer is still enqueued on the task the + * underlying k_itimer will be freed which results in a UAF in + * run_posix_cpu_timers() or on timerqueue related add/delete operations. + * If the timer is not enqueued, the failure is harmless + * + * - posix_cpu_timer_set(): Independent of the enqueued state that results in a + * transient failure which is user space visible (-ESRCH) for regular posix + * timers. But for the use case in do_cpu_nanosleep() it's the same UAF + * problem just that the timer is allocated on the stack. + * + * - posix_cpu_timer_rearm(): Timer is not enqueued at that point, but this + * silently ignores the rearm request, which is a functional problem as the + * timer wont expire anymore. + */ +static struct task_struct *timer_lock_sighand(struct k_itimer *timer, unsigned long *flags) +{ + enum pid_type type = clock_pid_type(timer->it_clock); + struct cpu_timer *ctmr = &timer->it.cpu; + + guard(rcu)(); + + for (;;) { + struct task_struct *t = pid_task(timer->it.cpu.pid, type); + + /* Fail if the task cannot be found. */ + if (!t) + break; + + /* Try to lock the task's sighand */ + if (lock_task_sighand(t, flags)) + return t; + + /* + * The next PID lookup might either fail or return the new + * leader. This is correct for both exit() and exec(). + */ + } + + /* + * If the timer is still enqueued, warn. There is nothing safe to do + * here as there might be two timers in there which are removed in + * parallel and that will cause more damage than good. This should never + * happen! + * + * Ensure that the stores to the timer and timerqueue are visible: + * + * __exit_signal() + * posix_cpu_timers*_exit() + * write_seqlock(seqlock) + * smp_wmb(); <------- + * __unhash_process() | !pid_task() + * ----> smp_rmb(); + * WARN_ON_ONCE(...) + */ + smp_rmb(); + WARN_ON_ONCE(ctmr->head || timerqueue_node_queued(&ctmr->node)); + return NULL; +} /* * Clean up a CPU-clock timer that is about to be destroyed. @@ -470,29 +573,13 @@ static void disarm_timer(struct k_itimer *timer, struct task_struct *p) */ static int posix_cpu_timer_del(struct k_itimer *timer) { - struct cpu_timer *ctmr = &timer->it.cpu; - struct sighand_struct *sighand; struct task_struct *p; unsigned long flags; int ret = 0; - rcu_read_lock(); - p = cpu_timer_task_rcu(timer); - if (!p) - goto out; + p = timer_lock_sighand(timer, &flags); - /* - * Protect against sighand release/switch in exit/exec and process/ - * thread timer list entry concurrent read/writes. - */ - sighand = lock_task_sighand(p, &flags); - if (unlikely(sighand == NULL)) { - /* - * This raced with the reaping of the task. The exit cleanup - * should have removed this timer from the timer queue. - */ - WARN_ON_ONCE(ctmr->head || timerqueue_node_queued(&ctmr->node)); - } else { + if (likely(p)) { if (timer->it.cpu.firing) { /* * Prevent signal delivery. The timer cannot be dequeued @@ -508,11 +595,8 @@ static int posix_cpu_timer_del(struct k_itimer *timer) unlock_task_sighand(p, &flags); } -out: - rcu_read_unlock(); - if (!ret) { - put_pid(ctmr->pid); + put_pid(timer->it.cpu.pid); timer->it_status = POSIX_TIMER_DISARMED; } return ret; @@ -626,21 +710,17 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock); struct cpu_timer *ctmr = &timer->it.cpu; u64 old_expires, new_expires, now; - struct sighand_struct *sighand; struct task_struct *p; unsigned long flags; int ret = 0; - rcu_read_lock(); - p = cpu_timer_task_rcu(timer); - if (!p) { - /* - * If p has just been reaped, we can no - * longer get any information about it at all. - */ - rcu_read_unlock(); + p = timer_lock_sighand(timer, &flags); + /* + * If p has just been reaped, we can no longer get any information about + * it at all. + */ + if (!p) return -ESRCH; - } /* * Use the to_ktime conversion because that clamps the maximum @@ -648,20 +728,6 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, */ new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value)); - /* - * Protect against sighand release/switch in exit/exec and p->cpu_timers - * and p->signal->cpu_timers read/write in arm_timer() - */ - sighand = lock_task_sighand(p, &flags); - /* - * If p has just been reaped, we can no - * longer get any information about it at all. - */ - if (unlikely(sighand == NULL)) { - rcu_read_unlock(); - return -ESRCH; - } - /* Retrieve the current expiry time before disarming the timer */ old_expires = cpu_timer_getexpires(ctmr); @@ -698,7 +764,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, /* Retry if the timer expiry is running concurrently */ if (unlikely(ret)) { unlock_task_sighand(p, &flags); - goto out; + return ret; } /* Convert relative expiry time to absolute */ @@ -733,8 +799,6 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, */ if (!sigev_none && new_expires && now >= new_expires) cpu_timer_fire(timer); -out: - rcu_read_unlock(); return ret; } @@ -1018,19 +1082,12 @@ static void check_process_timers(struct task_struct *tsk, static bool posix_cpu_timer_rearm(struct k_itimer *timer) { clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock); - struct sighand_struct *sighand; struct task_struct *p; unsigned long flags; u64 now; - guard(rcu)(); - p = cpu_timer_task_rcu(timer); - if (!p) - return true; - - /* Protect timer list r/w in arm_timer() */ - sighand = lock_task_sighand(p, &flags); - if (unlikely(sighand == NULL)) + p = timer_lock_sighand(timer, &flags); + if (unlikely(!p)) return true; /* -- cgit v1.2.3 From 15d9968b68e848a1a38ca875ba553b05dadae03d Mon Sep 17 00:00:00 2001 From: Yu Peng Date: Wed, 3 Jun 2026 14:25:32 +0800 Subject: tracing/synthetic: Free pending field on error path Some __create_synth_event() error paths run after parse_synth_field() succeeds but before the field is stored in fields[]. The common cleanup then misses the field. Free it before freeing argv. Link: https://patch.msgid.link/20260603062533.1096320-1-pengyu@kylinos.cn Signed-off-by: Yu Peng Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_synth.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c index e6871230bde9..cdd5b9332835 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -1446,13 +1446,13 @@ static int __create_synth_event(const char *name, const char *raw_fields) if (cmd_version > 1 && n_fields_this_loop >= 1) { synth_err(SYNTH_ERR_INVALID_CMD, errpos(field_str)); ret = -EINVAL; - goto err_free_arg; + goto err_free_field; } if (n_fields == SYNTH_FIELDS_MAX) { synth_err(SYNTH_ERR_TOO_MANY_FIELDS, 0); ret = -EINVAL; - goto err_free_arg; + goto err_free_field; } fields[n_fields++] = field; @@ -1491,6 +1491,8 @@ static int __create_synth_event(const char *name, const char *raw_fields) kfree(saved_fields); return ret; + err_free_field: + free_synth_field(field); err_free_arg: argv_free(argv); err: -- cgit v1.2.3 From c37e0a4b79a6bbb96ce5ffe279d7c001e20529e0 Mon Sep 17 00:00:00 2001 From: Hui Wang Date: Sun, 7 Jun 2026 15:24:30 +0800 Subject: ring-buffer: Fix event length with forced 8-byte alignment When RB_FORCE_8BYTE_ALIGNMENT is true, rb_calculate_event_length() reserves the space of event->array[0] for placing the data length and rb_update_event() stores the data length in event->array[0] accordingly. As a result the whole event length will add extra 4 bytes for sizeof(event.array[0]) unconditionally. But ring_buffer_event_length() only subtracts the sizeof(event->array[0]) for events larger than RB_MAX_SMALL_DATA + sizeof(event->array[0]). As a result, small events on architectures with RB_FORCE_8BYTE_ALIGNMENT=true report a data length that is 4 bytes larger than expected. To fix it, add the RB_FORCE_8BYTE_ALIGNMENT as a condition to subtract the size of that length field whenever RB_FORCE_8BYTE_ALIGNMENT is true. This issue is observed in a riscv64 kernel with CONFIG_HAVE_64BIT_ALIGNED_ACCESS set to y, when we run ftrace selftest trace_marker_raw.tc, we get the weird log: for cases where the id is 1..100, the number of data field is 8*N, but once id exceeds 100, the number of data field becomes 8*N+4: # 1 buf: 58 00 00 00 80 5e d1 63 (number of data field is 8*1) ... # a buf: 58 ... (number of data field is 8*2) ... # 64 buf: 58 ... (number of data field is 8*13) # 65 buf: 58 ... (number of data field is 8*13+4) After applying this change, the number of data field keeps being 8*N+4 consistently. Link: https://patch.msgid.link/20260607072431.125633-2-hui.wang@canonical.com Fixes: 2271048d1b3b ("ring-buffer: Do 8 byte alignment for 64 bit that can not handle 4 byte align") Signed-off-by: Hui Wang Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 56a328e94395..d9af2bbaf9c0 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -270,7 +270,8 @@ unsigned ring_buffer_event_length(struct ring_buffer_event *event) if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) return length; length -= RB_EVNT_HDR_SIZE; - if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) + if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0]) || + RB_FORCE_8BYTE_ALIGNMENT) length -= sizeof(event->array[0]); return length; } -- cgit v1.2.3 From fe58f457ad8d0a2bef4e053cfecca4b5cd266b1a Mon Sep 17 00:00:00 2001 From: Crystal Wood Date: Mon, 8 Jun 2026 23:54:30 -0500 Subject: tracing/osnoise: Call synchronize_rcu() when unregistering This ensures that any RCU readers traversing the instance list have finished, before releasing the reference on the tracer that the instance points to. Cc: stable@vger.kernel.org Fixes: a6ed2aee54644 ("tracing: Switch to kvfree_rcu() API") Link: https://patch.msgid.link/20260609045430.1589786-1-crwood@redhat.com Suggested-by: Steven Rostedt Signed-off-by: Crystal Wood Signed-off-by: Steven Rostedt --- kernel/trace/trace_osnoise.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 5e83c4f6f2b4..0e1265acd1cc 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -179,7 +179,9 @@ static void osnoise_unregister_instance(struct trace_array *tr) if (!found) return; - kvfree_rcu_mightsleep(inst); + /* Do a full sync to ensure that tr remains valid, not just inst */ + synchronize_rcu(); + kvfree(inst); } /* -- cgit v1.2.3 From a20b08de862c2983eac183b7560ad678acb58608 Mon Sep 17 00:00:00 2001 From: "Wayen.Yan" Date: Thu, 11 Jun 2026 11:52:57 +0800 Subject: tracing: Remove unused ret assignment in tracing_set_tracer() In tracing_set_tracer(), the assignment 'ret = 0' following the __tracing_resize_ring_buffer() error check is a dead store. After this point, all subsequent code paths either return with a constant value (-EINVAL, 0, -EBUSY) or reassign ret before reading it (tracing_arm_snapshot_locked, tracer_init). Remove the unnecessary assignment. No functional change. Link: https://patch.msgid.link/6a2a37c4.f0a9eb5a.2fc603.7724@mx.google.com Signed-off-by: Wayen.Yan Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 1146b83b711a..299f5ab630b9 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5015,7 +5015,6 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) RING_BUFFER_ALL_CPUS); if (ret < 0) return ret; - ret = 0; } list_for_each_entry(t, &tr->tracers, list) { -- cgit v1.2.3 From af05b4e06279bbe34f8044b1e82f0725b5da91b7 Mon Sep 17 00:00:00 2001 From: David Carlier Date: Tue, 16 Jun 2026 18:55:38 +0100 Subject: ring-buffer: Fix ring_buffer_read_page() copying only one event per page Commit 8928e4a3be34 ("ring-buffer: Show persistent buffer dropped events in trace_pipe file") split the "commit" variable in ring_buffer_read_page() into "commit" (raw) and "size" (masked page size), but the inner copy loop's terminator was changed to compare rpos against "event_size" instead of "size". rpos is the cumulative read offset within the page; event_size is the length of the single event just copied. The loop thus breaks after the first event, so only one event is copied per call. This regresses the per-event memcpy path (partial reads, the active commit page, and mapped/remote buffers) used by splice/trace_pipe_raw and mmap consumers into a one-event-at-a-time read. Compare rpos against the page size as the original code did. Link: https://patch.msgid.link/20260616175538.111628-1-devnexen@gmail.com Fixes: 8928e4a3be34 ("ring-buffer: Show persistent buffer dropped events in trace_pipe file") Signed-off-by: David Carlier Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index d9af2bbaf9c0..12a83d9ffd0a 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7175,7 +7175,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, rpos = reader->read; pos += event_size; - if (rpos >= event_size) + if (rpos >= size) break; event = rb_reader_event(cpu_buffer); -- cgit v1.2.3 From d5c6785f94ead7cd76b38af301ac63cb673485bc Mon Sep 17 00:00:00 2001 From: Ben Dooks Date: Wed, 17 Jun 2026 11:58:22 +0100 Subject: tracing: Make tracepoint_printk static as not exported The tracepoint_printk symbol is not exported, so make it static to remove the following sparse warning: kernel/trace/trace.c:90:5: warning: symbol 'tracepoint_printk' was not declared. Should it be static? Fixes: dd293df6395a2 ("tracing: Move trace sysctls into trace.c") Link: https://patch.msgid.link/20260617105822.904164-1-ben.dooks@codethink.co.uk Signed-off-by: Ben Dooks Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 299f5ab630b9..18710c190c92 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -87,7 +87,7 @@ void __init disable_tracing_selftest(const char *reason) /* Pipe tracepoints to printk */ static struct trace_iterator *tracepoint_print_iter; -int tracepoint_printk; +static int tracepoint_printk; static bool tracepoint_printk_stop_on_boot __initdata; static bool traceoff_after_boot __initdata; static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key); -- cgit v1.2.3 From c3e94604675e3db186111b8942650d86577df9b0 Mon Sep 17 00:00:00 2001 From: Yuanhe Shu Date: Wed, 24 Jun 2026 14:17:15 +0800 Subject: tracing: Fix NULL pointer dereference in func_set_flag() func_set_flag() dereferences tr->current_trace_flags before verifying that the current tracer is actually the function tracer. When the active tracer has been switched away from "function" (e.g., to "wakeup_rt"), tr->current_trace_flags can be NULL, leading to a NULL pointer dereference and kernel crash. The call chain that triggers this is: trace_options_write() -> __set_tracer_option() -> trace->set_flag() /* func_set_flag */ In func_set_flag(), the first operation is: if (!!set == !!(tr->current_trace_flags->val & bit)) This dereferences tr->current_trace_flags unconditionally. The safety check that guards against a non-function tracer: if (tr->current_trace != &function_trace) return 0; is placed *after* the dereference, which is too late. This was observed with the following crash dump: BUG: unable to handle page fault at 0000000000000000 RIP: func_set_flag+0xd Call Trace: __set_tracer_option+0x27 trace_options_write+0x75 vfs_write+0x12a ksys_write+0x66 do_syscall_64+0x5b RIP: ffffffff914c973d RSP: ff67ec88b01dfdf0 RFLAGS: 00010202 RAX: 0000000000000000 RBX: ff3a826e80354580 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff93918080 The disassembly confirms the fault: func_set_flag+0: mov 0x1f08(%rdi), %rax ; RAX = tr->current_trace_flags = NULL func_set_flag+13: mov (%rax), %eax ; page fault: dereference NULL At the time of the crash: tr->current_trace_flags = 0x0 (NULL) tr->current_trace = wakeup_rt_tracer (not function_trace) The scenario is that a process opens a function tracer option file (such as "func_stack_trace"), then the current tracer is switched to another tracer (e.g., "wakeup_rt"), which sets current_trace_flags to NULL. When the process subsequently writes to the option file, func_set_flag() is invoked and crashes on the NULL dereference. Fix this by moving the current_trace check before the current_trace_flags dereference, so that func_set_flag() returns early when the function tracer is not active. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260624061715.1445655-1-xiangzao@linux.alibaba.com Fixes: 76680d0d2825 ("tracing: Have function tracer define options per instance") Signed-off-by: Yuanhe Shu Signed-off-by: Steven Rostedt --- kernel/trace/trace_functions.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c index f283391a4dc8..cd37f2013758 100644 --- a/kernel/trace/trace_functions.c +++ b/kernel/trace/trace_functions.c @@ -458,12 +458,12 @@ func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) ftrace_func_t func; u32 new_flags; - /* Do nothing if already set. */ - if (!!set == !!(tr->current_trace_flags->val & bit)) + /* We can change this flag only when current tracer is function. */ + if (tr->current_trace != &function_trace) return 0; - /* We can change this flag only when not running. */ - if (tr->current_trace != &function_trace) + /* Do nothing if already set. */ + if (!!set == !!(tr->current_trace_flags->val & bit)) return 0; new_flags = (tr->current_trace_flags->val & ~bit) | (set ? bit : 0); -- cgit v1.2.3 From 0a6070839b1ef276d5b05bedfb787743e140fb17 Mon Sep 17 00:00:00 2001 From: Huihui Huang Date: Wed, 1 Jul 2026 18:28:46 +0800 Subject: tracing: Prevent out-of-bounds read in glob matching String event fields are not necessarily NUL-terminated, so the filter predicate functions (filter_pred_string(), filter_pred_strloc() and filter_pred_strrelloc()) pass the field length to the regex match callbacks, and the length-aware matchers honour it. regex_match_glob() was the exception: it ignored the length and called glob_match(), which scans the string until it hits a NUL byte. Some string fields are not NUL-terminated. One example is the dynamic char array of the xfs_* namespace tracepoints, which is copied without a trailing NUL. For such a field, glob matching reads past the end of the event field, causing a KASAN slab-out-of-bounds read in glob_match(), reached via regex_match_glob() and filter_match_preds() from the xfs_lookup tracepoint. Add a length-bounded glob_match_len() and use it from regex_match_glob() so glob matching always stops at the field boundary. The matching loop is factored into a shared helper so glob_match() keeps its behaviour. Fixes: 60f1d5e3bac4 ("ftrace: Support full glob matching") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/da1aaf125fc3b63320b0c540fd6afa7c3d5b4f1a.1782836943.git.hhhuang@smu.edu.sg Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Zhengchuan Liang Reported-by: Xin Liu Assisted-by: Codex:GPT-5.4 Signed-off-by: Huihui Huang Signed-off-by: Ren Wei Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_filter.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 609325f57942..6385cd662d8d 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1056,11 +1056,9 @@ static int regex_match_end(char *str, struct regex *r, int len) return 0; } -static int regex_match_glob(char *str, struct regex *r, int len __maybe_unused) +static int regex_match_glob(char *str, struct regex *r, int len) { - if (glob_match(r->pattern, str)) - return 1; - return 0; + return glob_match_len(r->pattern, str, len) ? 1 : 0; } /** -- cgit v1.2.3 From 1e67bb60bb03518d3bdd59a48c65d69e6d773bb8 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 1 Jul 2026 13:27:44 -0400 Subject: tracing: Add a no-rcu-check version of trace_##event##_enabled() Tracepoints require that RCU is watching. To prevent them from being used in places that RCU is not watching, the trace_##event() macro always calls rcu_is_watching() even when the event is not enabled and warns if RCU is not watching. This is to make sure a warning is triggered even if the tracepoint is never enabled (as it is only a bug when it is). It was noticed that tracepoints could be hidden within trace_#event#_enabled() calls, which are used to do extra work for the tracepoint only if the tracepoint is enabled. But this also can hide the fact that a tracepoint is placed in a location that can be called when RCU is not watching. Commit 9764e731ef6ab ("tracepoint: Add lockdep rcu_is_watching() check to trace_##name##_enabled()") added a check to the trace_##event##_enabled() macro to make sure RCU is watching when it is called to make sure not to hide the bug of a tracepoint being called when RCU is not watching. There is one case in the irq_disable tracepoint where it is within a trace_irq_disable_enabled() block, but it checks if RCU is watching, and if it isn't, it makes a call to ct_irq_enter() that makes RCU watch again. But because trace_irq_disable_enabled() now checks if RCU is watching and will trigger if it isn't. This is a false warning as the code within the block handles this case. Add a new internal macro __trace_##event##_enabled() that doesn't check if RCU is watching, and convert the irq_enable/disable tracepoints over to it. Link: https://patch.msgid.link/20260701132744.6a7fc68b@robin Reported-by: Geert Uytterhoeven Closes: https://lore.kernel.org/all/CAMuHMdXud_RpWag_hFqa2ByBGRxg6KnxGL1ObCWZrpTsk3TfAw@mail.gmail.com/ Fixes: 9764e731ef6ab ("tracepoint: Add lockdep rcu_is_watching() check to trace_##name##_enabled()") Tested-by: Geert Uytterhoeven Signed-off-by: Steven Rostedt --- kernel/trace/trace_preemptirq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_preemptirq.c b/kernel/trace/trace_preemptirq.c index 0c42b15c3800..b63e3558948f 100644 --- a/kernel/trace/trace_preemptirq.c +++ b/kernel/trace/trace_preemptirq.c @@ -30,7 +30,7 @@ #else #define trace(point, args) \ do { \ - if (trace_##point##_enabled()) { \ + if (__trace_##point##_enabled()) { \ bool exit_rcu = false; \ if (in_nmi()) \ break; \ -- cgit v1.2.3 From 50fd6dd755c6e48a38af2fa4621167eea56829c2 Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Tue, 7 Jul 2026 12:59:11 -0400 Subject: tracing/user_events: Fix use-after-free in user_event_mm_dup() user_event_mm_dup() walks the parent mm's enabler list locklessly under rcu_read_lock() during fork() (from copy_process()); it does not take event_mutex: rcu_read_lock(); list_for_each_entry_rcu(enabler, &old_mm->enablers, mm_enablers_link) enabler->event = user_event_get(orig->event); user_event_enabler_destroy() removes an enabler from that list with list_del_rcu() and then, without waiting for a grace period, drops the enabler's user_event reference with user_event_put() and frees the enabler with kfree(). A reader that loaded the enabler before the list_del_rcu() can still be walking it, which leads to two use-after-frees: - kfree(enabler) frees the enabler while that reader dereferences enabler->event. - user_event_put() may drop the last reference to the user_event, which is then freed (via delayed_destroy_user_event() on a work queue), while the same reader does user_event_get(orig->event) on it. Both are reachable by an unprivileged task that can open user_events_data: one multithreaded process that registers an enabler and then concurrently unregisters it and calls fork() triggers the race. KASAN reports a slab-use-after-free in user_event_mm_dup() during clone(), with a "refcount_t: addition on 0" warning when the user_event is freed. The enabler use-after-free was found first; the user_event one was reported by XIAO WU, and the earlier enabler-only fix did not address it. Defer both the user_event_put() and the kfree(enabler) to a work item queued with queue_rcu_work(), so they run only after an RCU grace period, once all readers walking the enabler list have finished. The put must run in process context because user_event_put() takes event_mutex on the last reference, so a work queue is used rather than call_rcu(). The now-unlocked put lets the locked argument of user_event_enabler_destroy() be removed; all callers are updated. Fixes: 7235759084a4 ("tracing/user_events: Use remote writes for event enablement") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260707165912.2560537-2-michael.bommarito@gmail.com Reported-by: XIAO WU Closes: https://lore.kernel.org/all/tencent_89647CE40DC452B891C65C94D1B271DE8E07@qq.com/ Suggested-by: Beau Belgrave Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Michael Bommarito Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_user.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index c4ba484f7b38..8c82ecb735f4 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -109,6 +109,9 @@ struct user_event_enabler { /* Track enable bit, flags, etc. Aligned for bitops. */ unsigned long values; + + /* Defer the event put and enabler free past an RCU grace period. */ + struct rcu_work put_rwork; }; /* Bits 0-5 are for the bit to update upon enable/disable (0-63 allowed) */ @@ -396,17 +399,39 @@ error: return NULL; }; -static void user_event_enabler_destroy(struct user_event_enabler *enabler, - bool locked) +static void delayed_user_event_enabler_put(struct work_struct *work) { - list_del_rcu(&enabler->mm_enablers_link); + struct user_event_enabler *enabler = container_of(to_rcu_work(work), + struct user_event_enabler, put_rwork); /* No longer tracking the event via the enabler */ - user_event_put(enabler->event, locked); + user_event_put(enabler->event, false); + /* Run from queue_rcu_work(), the RCU grace period has elapsed */ kfree(enabler); } +static void user_event_enabler_destroy(struct user_event_enabler *enabler) +{ + list_del_rcu(&enabler->mm_enablers_link); + + /* + * The enabler is removed from an RCU-traversed list + * (user_event_mm_dup() walks mm->enablers under rcu_read_lock() only), + * and readers there dereference enabler->event and take a new ref on + * it. Both the put of that event reference and the free of the enabler + * therefore have to wait for a grace period so no reader can be looking + * at the enabler or racing the last put of its event. + * + * The put itself must not run in RCU context: when it drops the last + * reference user_event_put() takes event_mutex, which cannot be taken + * from a softirq/RCU callback. Defer both to a work item scheduled + * after a grace period via queue_rcu_work(). + */ + INIT_RCU_WORK(&enabler->put_rwork, delayed_user_event_enabler_put); + queue_rcu_work(system_percpu_wq, &enabler->put_rwork); +} + static int user_event_mm_fault_in(struct user_event_mm *mm, unsigned long uaddr, int attempt) { @@ -464,7 +489,7 @@ static void user_event_enabler_fault_fixup(struct work_struct *work) /* User asked for enabler to be removed during fault */ if (test_bit(ENABLE_VAL_FREEING_BIT, ENABLE_BITOPS(enabler))) { - user_event_enabler_destroy(enabler, true); + user_event_enabler_destroy(enabler); goto out; } @@ -764,7 +789,7 @@ static void user_event_mm_destroy(struct user_event_mm *mm) struct user_event_enabler *enabler, *next; list_for_each_entry_safe(enabler, next, &mm->enablers, mm_enablers_link) - user_event_enabler_destroy(enabler, false); + user_event_enabler_destroy(enabler); mmdrop(mm->mm); kfree(mm); @@ -2645,7 +2670,7 @@ static long user_events_ioctl_unreg(unsigned long uarg) flags |= enabler->values & ENABLE_VAL_COMPAT_MASK; if (!test_bit(ENABLE_VAL_FAULTING_BIT, ENABLE_BITOPS(enabler))) - user_event_enabler_destroy(enabler, true); + user_event_enabler_destroy(enabler); /* Removed at least one */ ret = 0; -- cgit v1.2.3 From 05074bb90af94f2acbbc8f8ffaa507f914c273c8 Mon Sep 17 00:00:00 2001 From: Yu Peng Date: Wed, 3 Jun 2026 14:25:33 +0800 Subject: tracing/synthetic: Free type string on error path parse_synth_field() builds a "__data_loc ..." type string before assigning it to field->type. If the seq_buf check fails, the common cleanup cannot free the temporary string. Free it before leaving. Link: https://patch.msgid.link/20260603062533.1096320-2-pengyu@kylinos.cn Signed-off-by: Yu Peng Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_synth.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c index cdd5b9332835..dc15658a887c 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -839,8 +839,10 @@ static struct synth_field *parse_synth_field(int argc, char **argv, seq_buf_puts(&s, "__data_loc "); seq_buf_puts(&s, field->type); - if (WARN_ON_ONCE(!seq_buf_buffer_left(&s))) + if (WARN_ON_ONCE(!seq_buf_buffer_left(&s))) { + kfree(type); goto free; + } s.buffer[s.len] = '\0'; kfree(field->type); -- cgit v1.2.3 From 65dfde57d1e29ce2b76fc23dd565eccd5c0bc0f0 Mon Sep 17 00:00:00 2001 From: Ricardo Robaina Date: Thu, 2 Jul 2026 11:04:11 -0300 Subject: audit: fix potential integer overflow in audit_log_n_hex() The function calculates new_len as len << 1 for hex encoding. This has two overflow risks: the shift itself can overflow when len is large, and the result can be truncated when assigned to new_len (declared as int) from the size_t calculation. Fix by using check_shl_overflow() to catch shift overflow and changing new_len and loop counter i to size_t to prevent truncation. Cc: stable@vger.kernel.org Fixes: 168b7173959f ("AUDIT: Clean up logging of untrusted strings") Reviewed-by: Richard Guy Briggs Signed-off-by: Ricardo Robaina [PM: remove vertical whitspace noise] Signed-off-by: Paul Moore --- kernel/audit.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/audit.c b/kernel/audit.c index feaa4e2271d7..562476937fa7 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -62,6 +62,7 @@ #include #include #include +#include #include "audit.h" @@ -2080,7 +2081,8 @@ void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, size_t len) { - int i, avail, new_len; + int avail; + size_t i, new_len; unsigned char *ptr; struct sk_buff *skb; @@ -2090,7 +2092,12 @@ void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, BUG_ON(!ab->skb); skb = ab->skb; avail = skb_tailroom(skb); - new_len = len<<1; + + if (check_shl_overflow(len, 1, &new_len)) { + audit_log_format(ab, "?"); + return; + } + if (new_len >= avail) { /* Round the buffer request up to the next multiple */ new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); -- cgit v1.2.3 From 5948aaf64f81f217a25dcc2bf6c0779bca19566c Mon Sep 17 00:00:00 2001 From: Lee Jia Jie Date: Thu, 9 Jul 2026 21:56:19 +0800 Subject: perf/aux: Fix page UAF in map_range() map_range() reads rb->aux_pages[], rb->aux_nr_pages and rb->aux_pgoff via perf_mmap_to_page() while holding only event->mmap_mutex. Those fields are serialized by rb->aux_mutex, and mmap_mutex is per event. Thus, two events sharing one rb via PERF_EVENT_IOC_SET_OUTPUT can race rb_alloc_aux() with map_range(), leading to a page-UAF scenario as follows: CPU 0 CPU 1 ===== ===== rb_alloc_aux() map_range() [1]: allocate rb->aux_pages[0] [2]: rb->aux_nr_pages++ [3]: perf_mmap_to_page() returns rb->aux_pages[0] [4]: map it as VM_PFNMAP [5]: rb->aux_pgoff = 1 munmap the page [6]: free rb->aux_pages[0] Pages mapped as VM_PFNMAP have no refcount protection, so CPU 1 holds a mapping to a freed physical frame. Fix this by taking rb->aux_mutex across the page walk in map_range(). Fixes: b709eb872e19 ("perf: map pages in advance") Signed-off-by: Lee Jia Jie Signed-off-by: Ingo Molnar Cc: stable@vger.kernel.org Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Namhyung Kim --- kernel/events/core.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index d7f3e2c2ecb1..ba5bd6a78fe7 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7150,6 +7150,8 @@ static int map_range(struct perf_buffer *rb, struct vm_area_struct *vma) int err = 0; unsigned long pagenum; + guard(mutex)(&rb->aux_mutex); + /* * We map this as a VM_PFNMAP VMA. * -- cgit v1.2.3 From ec082d0b978b5fb4c11205ccce63587ac94c74e1 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Thu, 9 Jul 2026 17:00:15 +0100 Subject: tracing/remotes: Fix leak in trace_remote_alloc_buffer() error path If page allocation fails in trace_remote_alloc_buffer(), desc->nr_cpus is not yet incremented for the current CPU. As a consequence, on error, half-allocated rb_desc will not be freed in trace_remote_free_buffer(). Increment desc->nr_cpus as soon as the first allocation for the current CPU has succeeded. Link: https://patch.msgid.link/20260709160017.1729517-2-vdonnefort@google.com Fixes: 96e43537af54 ("tracing: Introduce trace remotes") Reported-by: Sashiko Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt --- kernel/trace/trace_remote.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index 2a6cc000ec98..d48042239d58 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -1006,6 +1006,8 @@ int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, if (!rb_desc->meta_va) goto err; + desc->nr_cpus++; + for (id = 0; id < nr_pages; id++) { rb_desc->page_va[id] = (unsigned long)__get_free_page(GFP_KERNEL); if (!rb_desc->page_va[id]) @@ -1013,7 +1015,6 @@ int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, rb_desc->nr_page_va++; } - desc->nr_cpus++; desc->struct_len += offsetof(struct ring_buffer_desc, page_va); desc->struct_len += struct_size(rb_desc, page_va, rb_desc->nr_page_va); rb_desc = __next_ring_buffer_desc(rb_desc); -- cgit v1.2.3 From d471d4f86e8689ad15309e49da8e5e4e9bb9ce87 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Thu, 9 Jul 2026 17:00:16 +0100 Subject: tracing/remotes: Fix struct_len in trace_remote_alloc_buffer() Pre-calculate desc->struct_len up-front in trace_remote_alloc_buffer() with trace_buffer_desc_size() to fix double-counting. While at it, use the accessor __first_ring_buffer_desc(). Link: https://patch.msgid.link/20260709160017.1729517-3-vdonnefort@google.com Fixes: 96e43537af54 ("tracing: Introduce trace remotes") Reported-by: Sashiko Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt --- kernel/trace/trace_remote.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index d48042239d58..0f6ef5c36d84 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -979,27 +979,22 @@ EXPORT_SYMBOL_GPL(trace_remote_free_buffer); int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, size_t buffer_size, const struct cpumask *cpumask) { + size_t min_desc_size = trace_buffer_desc_size(buffer_size, cpumask_weight(cpumask)); unsigned int nr_pages = max(DIV_ROUND_UP(buffer_size, PAGE_SIZE), 2UL) + 1; - void *desc_end = desc + desc_size; struct ring_buffer_desc *rb_desc; int cpu, ret = -ENOMEM; - if (desc_size < struct_size(desc, __data, 0)) + if (desc_size < min_desc_size) return -EINVAL; desc->nr_cpus = 0; - desc->struct_len = struct_size(desc, __data, 0); + desc->struct_len = min_desc_size; - rb_desc = (struct ring_buffer_desc *)&desc->__data[0]; + rb_desc = __first_ring_buffer_desc(desc); for_each_cpu(cpu, cpumask) { unsigned int id; - if ((void *)rb_desc + struct_size(rb_desc, page_va, nr_pages) > desc_end) { - ret = -EINVAL; - goto err; - } - rb_desc->cpu = cpu; rb_desc->nr_page_va = 0; rb_desc->meta_va = (unsigned long)__get_free_page(GFP_KERNEL); @@ -1015,8 +1010,6 @@ int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, rb_desc->nr_page_va++; } - desc->struct_len += offsetof(struct ring_buffer_desc, page_va); - desc->struct_len += struct_size(rb_desc, page_va, rb_desc->nr_page_va); rb_desc = __next_ring_buffer_desc(rb_desc); } -- cgit v1.2.3 From 601ddaceb861be7eb557278109966320a6f3478c Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Thu, 9 Jul 2026 17:00:17 +0100 Subject: ring-buffer: Allow sparse CPU masks in ring_buffer_desc() No user currently relies on sparse CPU masks, but the descriptor logic already supports them via linear fallback. Remove the arbitrary limitation. Link: https://patch.msgid.link/20260709160017.1729517-4-vdonnefort@google.com Fixes: 2e67fabd8b77 ("ring-buffer: Introduce ring-buffer remotes") Reported-by: Sashiko Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 12a83d9ffd0a..804ccae694d2 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2330,10 +2330,7 @@ static struct ring_buffer_desc *ring_buffer_desc(struct trace_buffer_desc *trace size_t len; int i; - if (!trace_desc) - return NULL; - - if (cpu >= trace_desc->nr_cpus) + if (!trace_desc || !trace_desc->nr_cpus) return NULL; end = (struct ring_buffer_desc *)((void *)trace_desc + trace_desc->struct_len); -- cgit v1.2.3