linux-stable.git/kernel, branch v6.13.5

tracing: Fix using ret variable in tracing_set_tracer()

2025-02-27T12:34:22+00:00

commit 22bec11a569983f39c6061cb82279e7de9e3bdfc upstream.

When the function tracing_set_tracer() switched over to using the guard()
infrastructure, it did not need to save the 'ret' variable and would just
return the value when an error arised, instead of setting ret and jumping
to an out label.

When CONFIG_TRACER_SNAPSHOT is enabled, it had code that expected the
"ret" variable to be initialized to zero and had set 'ret' while holding
an arch_spin_lock() (not used by guard), and then upon releasing the lock
it would check 'ret' and exit if set. But because ret was only set when an
error occurred while holding the locks, 'ret' would be used uninitialized
if there was no error. The code in the CONFIG_TRACER_SNAPSHOT block should
be self contain. Make sure 'ret' is also set when no error occurred.

Cc: Mathieu Desnoyers 
Link: https://lore.kernel.org/20250106111143.2f90ff65@gandalf.local.home
Reported-by: kernel test robot 
Reported-by: Dan Carpenter 
Closes: https://lore.kernel.org/r/202412271654.nJVBuwmF-lkp@intel.com/
Fixes: d33b10c0c73ad ("tracing: Switch trace.c code over to use guard()")
Signed-off-by: Steven Rostedt (Google) 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Do not add duplicate entries in subops manager ops

2025-02-27T12:34:21+00:00

commit 8eb4b09e0bbd30981305643229fe7640ad41b667 upstream.

Check if a function is already in the manager ops of a subops. A manager
ops contains multiple subops, and if two or more subops are tracing the
same function, the manager ops only needs a single entry in its hash.

Cc: stable@vger.kernel.org
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Cc: Sven Schnelle 
Cc: Vasily Gorbik 
Cc: Alexander Gordeev 
Link: https://lore.kernel.org/20250220202055.226762894@goodmis.org
Fixes: 4f554e955614f ("ftrace: Add ftrace_set_filter_ips function")
Tested-by: Heiko Carstens 
Reviewed-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix accounting of adding subops to a manager ops

2025-02-27T12:34:21+00:00

commit 38b14061947fa546491656e3f5e388d4fedf8dba upstream.

Function graph uses a subops and manager ops mechanism to attach to
ftrace.  The manager ops connects to ftrace and the functions it connects
to is defined by a list of subops that it manages.

The function hash that defines what the above ops attaches to limits the
functions to attach if the hash has any content. If the hash is empty, it
means to trace all functions.

The creation of the manager ops hash is done by iterating over all the
subops hashes. If any of the subops hashes is empty, it means that the
manager ops hash must trace all functions as well.

The issue is in the creation of the manager ops. When a second subops is
attached, a new hash is created by starting it as NULL and adding the
subops one at a time. But the NULL ops is mistaken as an empty hash, and
once an empty hash is found, it stops the loop of subops and just enables
all functions.

  # echo "f:myevent1 kernel_clone" >> /sys/kernel/tracing/dynamic_events
  # cat /sys/kernel/tracing/enabled_functions
kernel_clone (1)           	tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60

  # echo "f:myevent2 schedule_timeout" >> /sys/kernel/tracing/dynamic_events
  # cat /sys/kernel/tracing/enabled_functions
trace_initcall_start_cb (1)             tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
run_init_process (1)            tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
try_to_run_init_process (1)             tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
x86_pmu_show_pmu_cap (1)                tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
cleanup_rapl_pmus (1)                   tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
uncore_free_pcibus_map (1)              tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
uncore_types_exit (1)                   tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
uncore_pci_exit.part.0 (1)              tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
kvm_shutdown (1)                tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
vmx_dump_msrs (1)               tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
vmx_cleanup_l1d_flush (1)               tramp: 0xffffffffc0309000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
[..]

Fix this by initializing the new hash to NULL and if the hash is NULL do
not treat it as an empty hash but instead allocate by copying the content
of the first sub ops. Then on subsequent iterations, the new hash will not
be NULL, but the content of the previous subops. If that first subops
attached to all functions, then new hash may assume that the manager ops
also needs to attach to all functions.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Cc: Heiko Carstens 
Cc: Sven Schnelle 
Cc: Vasily Gorbik 
Cc: Alexander Gordeev 
Link: https://lore.kernel.org/20250220202055.060300046@goodmis.org
Fixes: 5fccc7552ccbc ("ftrace: Add subops logic to allow one ops to manage many")
Reviewed-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Correct preemption accounting for function tracing.

2025-02-27T12:34:21+00:00

commit 57b76bedc5c52c66968183b5ef57234894c25ce7 upstream.

The function tracer should record the preemption level at the point when
the function is invoked. If the tracing subsystem decrement the
preemption counter it needs to correct this before feeding the data into
the trace buffer. This was broken in the commit cited below while
shifting the preempt-disabled section.

Use tracing_gen_ctx_dec() which properly subtracts one from the
preemption counter on a preemptible kernel.

Cc: stable@vger.kernel.org
Cc: Wander Lairson Costa 
Cc: Masami Hiramatsu 
Cc: Mathieu Desnoyers 
Cc: Thomas Gleixner 
Link: https://lore.kernel.org/20250220140749.pfw8qoNZ@linutronix.de
Fixes: ce5e48036c9e7 ("ftrace: disable preemption when recursion locked")
Signed-off-by: Sebastian Andrzej Siewior 
Tested-by: Wander Lairson Costa 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

acct: block access to kernel internal filesystems

2025-02-27T12:34:21+00:00

commit 890ed45bde808c422c3c27d3285fc45affa0f930 upstream.

There's no point in allowing anything kernel internal nor procfs or
sysfs.

Link: https://lore.kernel.org/r/20250127091811.3183623-1-quzicheng@huawei.com
Link: https://lore.kernel.org/r/20250211-work-acct-v1-2-1c16aecab8b3@kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Amir Goldstein 
Reported-by: Zicheng Qu 
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner 
Signed-off-by: Greg Kroah-Hartman

acct: perform last write from workqueue

2025-02-27T12:34:21+00:00

commit 56d5f3eba3f5de0efdd556de4ef381e109b973a9 upstream.

In [1] it was reported that the acct(2) system call can be used to
trigger NULL deref in cases where it is set to write to a file that
triggers an internal lookup. This can e.g., happen when pointing acc(2)
to /sys/power/resume. At the point the where the write to this file
happens the calling task has already exited and called exit_fs(). A
lookup will thus trigger a NULL-deref when accessing current->fs.

Reorganize the code so that the the final write happens from the
workqueue but with the caller's credentials. This preserves the
(strange) permission model and has almost no regression risk.

This api should stop to exist though.

Link: https://lore.kernel.org/r/20250127091811.3183623-1-quzicheng@huawei.com [1]
Link: https://lore.kernel.org/r/20250211-work-acct-v1-1-1c16aecab8b3@kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Zicheng Qu 
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner 
Signed-off-by: Greg Kroah-Hartman

sched: Compact RSEQ concurrency IDs with reduced threads and affinity

2025-02-27T12:34:18+00:00

[ Upstream commit 02d954c0fdf91845169cdacc7405b120f90afe01 ]

When a process reduces its number of threads or clears bits in its CPU
affinity mask, the mm_cid allocation should eventually converge towards
smaller values.

However, the change introduced by:

commit 7e019dcc470f ("sched: Improve cache locality of RSEQ concurrency
IDs for intermittent workloads")

adds a per-mm/CPU recent_cid which is never unset unless a thread
migrates.

This is a tradeoff between:

A) Preserving cache locality after a transition from many threads to few
   threads, or after reducing the hamming weight of the allowed CPU mask.

B) Making the mm_cid upper bounds wrt nr threads and allowed CPU mask
   easy to document and understand.

C) Allowing applications to eventually react to mm_cid compaction after
   reduction of the nr threads or allowed CPU mask, making the tracking
   of mm_cid compaction easier by shrinking it back towards 0 or not.

D) Making sure applications that periodically reduce and then increase
   again the nr threads or allowed CPU mask still benefit from good
   cache locality with mm_cid.

Introduce the following changes:

* After shrinking the number of threads or reducing the number of
  allowed CPUs, reduce the value of max_nr_cid so expansion of CID
  allocation will preserve cache locality if the number of threads or
  allowed CPUs increase again.

* Only re-use a recent_cid if it is within the max_nr_cid upper bound,
  else find the first available CID.

Fixes: 7e019dcc470f ("sched: Improve cache locality of RSEQ concurrency IDs for intermittent workloads")
Signed-off-by: Mathieu Desnoyers 
Signed-off-by: Gabriele Monaco 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Gabriele Monaco 
Link: https://lkml.kernel.org/r/20250210153253.460471-2-gmonaco@redhat.com
Signed-off-by: Sasha Levin

bpf: skip non exist keys in generic_map_lookup_batch

2025-02-27T12:34:18+00:00

[ Upstream commit 5644c6b50ffee0a56c1e01430a8c88e34decb120 ]

The generic_map_lookup_batch currently returns EINTR if it fails with
ENOENT and retries several times on bpf_map_copy_value. The next batch
would start from the same location, presuming it's a transient issue.
This is incorrect if a map can actually have "holes", i.e.
"get_next_key" can return a key that does not point to a valid value. At
least the array of maps type may contain such holes legitly. Right now
these holes show up, generic batch lookup cannot proceed any more. It
will always fail with EINTR errors.

Rather, do not retry in generic_map_lookup_batch. If it finds a non
existing element, skip to the next key. This simple solution comes with
a price that transient errors may not be recovered, and the iteration
might cycle back to the first key under parallel deletion. For example,
Hou Tao pointed out a following scenario:

For LPM trie map:
(1) ->map_get_next_key(map, prev_key, key) returns a valid key

(2) bpf_map_copy_value() return -ENOMENT
It means the key must be deleted concurrently.

(3) goto next_key
It swaps the prev_key and key

(4) ->map_get_next_key(map, prev_key, key) again
prev_key points to a non-existing key, for LPM trie it will treat just
like prev_key=NULL case, the returned key will be duplicated.

With the retry logic, the iteration can continue to the key next to the
deleted one. But if we directly skip to the next key, the iteration loop
would restart from the first key for the lpm_trie type.

However, not all races may be recovered. For example, if current key is
deleted after instead of before bpf_map_copy_value, or if the prev_key
also gets deleted, then the loop will still restart from the first key
for lpm_tire anyway. For generic lookup it might be better to stay
simple, i.e. just skip to the next key. To guarantee that the output
keys are not duplicated, it is better to implement map type specific
batch operations, which can properly lock the trie and synchronize with
concurrent mutators.

Fixes: cb4d03ab499d ("bpf: Add generic support for lookup batch op")
Closes: https://lore.kernel.org/bpf/Z6JXtA1M5jAZx8xD@debian.debian/
Signed-off-by: Yan Zhai
Acked-by: Hou Tao
Link: https://lore.kernel.org/r/85618439eea75930630685c467ccefeac0942e2b.1739171594.git.yan@cloudflare.com
Signed-off-by: Alexei Starovoitov
Signed-off-by: Sasha Levin

bpf: Fix softlockup in arena_map_free on 64k page kernel

2025-02-27T12:34:16+00:00

[ Upstream commit 517e8a7835e8cfb398a0aeb0133de50e31cae32b ]

On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y,
arena_htab tests cause a segmentation fault and soft lockup.
The same failure is not observed with 4k pages on aarch64.

It turns out arena_map_free() is calling
apply_to_existing_page_range() with the address returned by
bpf_arena_get_kern_vm_start().  If this address is not page-aligned
the code ends up calling apply_to_pte_range() with that unaligned
address causing soft lockup.

Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the
division by 2 in bpf_arena_get_kern_vm_start() returns
a page-aligned value.

Fixes: 317460317a02 ("bpf: Introduce bpf_arena.")
Reported-by: Colm Harrington 
Suggested-by: Alexei Starovoitov 
Signed-off-by: Alan Maguire 
Link: https://lore.kernel.org/r/20250205170059.427458-1-alan.maguire@oracle.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

net: Add rx_skb of kfree_skb to raw_tp_null_args[].

2025-02-27T12:34:16+00:00

[ Upstream commit 5da7e15fb5a12e78de974d8908f348e279922ce9 ]

Yan Zhai reported a BPF prog could trigger a null-ptr-deref [0]
in trace_kfree_skb if the prog does not check if rx_sk is NULL.

Commit c53795d48ee8 ("net: add rx_sk to trace_kfree_skb") added
rx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL.

Let's add kfree_skb to raw_tp_null_args[] to let the BPF verifier
validate such a prog and prevent the issue.

Now we fail to load such a prog:

  libbpf: prog 'drop': -- BEGIN PROG LOAD LOG --
  0: R1=ctx() R10=fp0
  ; int BPF_PROG(drop, struct sk_buff *skb, void *location, @ kfree_skb_sk_null.bpf.c:21
  0: (79) r3 = *(u64 *)(r1 +24)
  func 'kfree_skb' arg3 has btf_id 5253 type STRUCT 'sock'
  1: R1=ctx() R3_w=trusted_ptr_or_null_sock(id=1)
  ; bpf_printk("sk: %d, %d\n", sk, sk->__sk_common.skc_family); @ kfree_skb_sk_null.bpf.c:24
  1: (69) r4 = *(u16 *)(r3 +16)
  R3 invalid mem access 'trusted_ptr_or_null_'
  processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
  -- END PROG LOAD LOG --

Note this fix requires commit 838a10bd2ebf ("bpf: Augment raw_tp
arguments with PTR_MAYBE_NULL").

[0]:
BUG: kernel NULL pointer dereference, address: 0000000000000010
 PF: supervisor read access in kernel mode
 PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
PREEMPT SMP
RIP: 0010:bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d
Call Trace:
 
 ? __die+0x1f/0x60
 ? page_fault_oops+0x148/0x420
 ? search_bpf_extables+0x5b/0x70
 ? fixup_exception+0x27/0x2c0
 ? exc_page_fault+0x75/0x170
 ? asm_exc_page_fault+0x22/0x30
 ? bpf_prog_5e21a6db8fcff1aa_drop+0x10/0x2d
 bpf_trace_run4+0x68/0xd0
 ? unix_stream_connect+0x1f4/0x6f0
 sk_skb_reason_drop+0x90/0x120
 unix_stream_connect+0x1f4/0x6f0
 __sys_connect+0x7f/0xb0
 __x64_sys_connect+0x14/0x20
 do_syscall_64+0x47/0xc30
 entry_SYSCALL_64_after_hwframe+0x4b/0x53

Fixes: c53795d48ee8 ("net: add rx_sk to trace_kfree_skb")
Reported-by: Yan Zhai 
Closes: https://lore.kernel.org/netdev/Z50zebTRzI962e6X@debian.debian/
Signed-off-by: Kuniyuki Iwashima 
Tested-by: Yan Zhai 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/r/20250201030142.62703-1-kuniyu@amazon.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin