linux-stable.git/kernel/bpf, branch v6.12.95

bpf: use kvfree() for replaced sysctl write buffer

2026-07-04T11:43:33+00:00

commit 4c21b5927d4364bfe7365f2700da5fea0ed0d004 upstream.

proc_sys_call_handler() allocates its temporary sysctl buffer with
kvzalloc() and passes it to __cgroup_bpf_run_filter_sysctl(). Since
kvzalloc() may fall back to vmalloc() for large allocations, freeing
that buffer with kfree() is wrong and can corrupt memory.

Use kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc
allocations.

The bug was first flagged by an experimental analysis tool we are
developing for kernel memory-management bugs while analyzing
v6.13-rc1. The tool is still under development and is not yet publicly
available. Manual inspection confirms that the bug is still
present in v7.1-rc5.

Reproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with
KASAN and CONFIG_FAILSLAB enabled. To exercise the replacement path, the
test tree also included the accompanying fix for the stale ret == 1
check in __cgroup_bpf_run_filter_sysctl(). The reproducer confines
failslab injections to the proc_sys_call_handler() range, uses
stacktrace-depth=32, and injects fail-nth=1 while writing 8191 bytes to
/proc/sys/kernel/domainname from a task in the target cgroup. Under
that setup, fail-nth=1 triggered the fault:

  BUG: unable to handle page fault for address: ffffeb0200024d48
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: Oops: 0000  SMP KASAN NOPTI
  CPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted 7.1.0-rc4-00686-g97625979a5d4  PREEMPT(lazy)
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
  RIP: 0010:kfree+0x6e/0x510
  ...
  Call Trace:
   
   ? __cgroup_bpf_run_filter_sysctl+0x626/0xc30
   __cgroup_bpf_run_filter_sysctl+0x74d/0xc30
   ? __pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10
   ? srso_return_thunk+0x5/0x5f
   ? __kvmalloc_node_noprof+0x345/0x870
   ? proc_sys_call_handler+0x250/0x480
   ? srso_return_thunk+0x5/0x5f
   proc_sys_call_handler+0x3a2/0x480
   ? __pfx_proc_sys_call_handler+0x10/0x10
   ? srso_return_thunk+0x5/0x5f
   ? selinux_file_permission+0x39f/0x500
   ? srso_return_thunk+0x5/0x5f
   ? lock_is_held_type+0x9e/0x120
   vfs_write+0x98e/0x1000
   ...
   

With this fix applied on top of the same test setup, rerunning the
reproducer with fail-nth=1 yields no corresponding Oops reports.

Fixes: 4508943794ef ("proc: use kvzalloc for our kernel buffer")
Cc: stable@vger.kernel.org

Reviewed-by: Emil Tsalapatis 
Reviewed-by: Jiayuan Chen 
Acked-by: Yonghong Song 
Signed-off-by: Zilin Guan 
Signed-off-by: Dawei Feng 
Link: https://lore.kernel.org/r/20260603105317.944304-3-dawei.feng@seu.edu.cn
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Greg Kroah-Hartman

remove pointless includes of

2026-06-09T10:25:43+00:00

[ Upstream commit be5498cac2ddb112c5bd7433d5e834a1a2493427 ]

some of those used to be needed, some had been cargo-culted for
no reason...

Reviewed-by: Christian Brauner 
Signed-off-by: Al Viro 
Stable-dep-of: ea5fe6a73ca5 ("net/handshake: Drain pending requests at net namespace exit")
Signed-off-by: Sasha Levin

bpf: Validate node_id in arena_alloc_pages()

2026-05-23T11:04:42+00:00

[ Upstream commit 2845989f2ebaf7848e4eccf9a779daf3156ea0a5 ]

arena_alloc_pages() accepts a plain int node_id and forwards it through
the entire allocation chain without any bounds checking.

Validate node_id before passing it down the allocation chain in
arena_alloc_pages().

Fixes: 317460317a02 ("bpf: Introduce bpf_arena.")
Signed-off-by: Puranjay Mohan 
Reviewed-by: Emil Tsalapatis 
Link: https://lore.kernel.org/r/20260417152135.1383754-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: allow UTF-8 literals in bpf_bprintf_prepare()

2026-05-23T11:04:42+00:00

[ Upstream commit b960430ea8862ef37ce53c8bf74a8dc79d3f2404 ]

bpf_bprintf_prepare() only needs ASCII parsing for conversion
specifiers. Plain text can safely carry bytes >= 0x80, so allow
UTF-8 literals outside '%' sequences while keeping ASCII control
bytes rejected and format specifiers ASCII-only.

This keeps existing parsing rules for format directives unchanged,
while allowing helpers such as bpf_trace_printk() to emit UTF-8
literal text.

Update test_snprintf_negative() in the same commit so selftests keep
matching the new plain-text vs format-specifier split during bisection.

Fixes: 48cac3f4a96d ("bpf: Implement formatted output helpers with bstr_printf")
Signed-off-by: Yihan Ding 
Acked-by: Paul Chaignon 
Link: https://lore.kernel.org/r/20260416120142.1420646-2-dingyihan@uniontech.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: Fix NULL deref in map_kptr_match_type for scalar regs

2026-05-23T11:04:42+00:00

[ Upstream commit 4d0a375887ab4d49e4da1ff10f9606cab8f7c3ad ]

Commit ab6c637ad027 ("bpf: Fix a bpf_kptr_xchg() issue with local
kptr") refactored map_kptr_match_type() to branch on btf_is_kernel()
before checking base_type(). A scalar register stored into a kptr
slot has no btf, so the btf_is_kernel(reg->btf) call dereferences
NULL.

Move the base_type() != PTR_TO_BTF_ID guard before any reg->btf
access.

Fixes: ab6c637ad027 ("bpf: Fix a bpf_kptr_xchg() issue with local kptr")
Reported-by: Hiker Cl 
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221372
Signed-off-by: Mykyta Yatsenko 
Acked-by: Paul Chaignon 
Link: https://lore.kernel.org/r/20260416-kptr_crash-v1-1-5589356584b4@meta.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: Fix OOB in pcpu_init_value

2026-05-23T11:04:25+00:00

[ Upstream commit 576afddfee8d1108ee299bf10f581593540d1a36 ]

An out-of-bounds read occurs when copying element from a
BPF_MAP_TYPE_CGROUP_STORAGE map to another pcpu map with the
same value_size that is not rounded up to 8 bytes.

The issue happens when:
1. A CGROUP_STORAGE map is created with value_size not aligned to
   8 bytes (e.g., 4 bytes)
2. A pcpu map is created with the same value_size (e.g., 4 bytes)
3. Update element in 2 with data in 1

pcpu_init_value assumes that all sources are rounded up to 8 bytes,
and invokes copy_map_value_long to make a data copy, However, the
assumption doesn't stand since there are some cases where the source
may not be rounded up to 8 bytes, e.g., CGROUP_STORAGE, skb->data.
the verifier verifies exactly the size that the source claims, not
the size rounded up to 8 bytes by kernel, an OOB happens when the
source has only 4 bytes while the copy size(4) is rounded up to 8.

Fixes: d3bec0138bfb ("bpf: Zero-fill re-used per-cpu map element")
Reported-by: Kaiyan Mei 
Closes: https://lore.kernel.org/all/14e6c70c.6c121.19c0399d948.Coremail.kaiyanm@hust.edu.cn/
Link: https://lore.kernel.org/r/420FEEDDC768A4BE+20260402074236.2187154-1-xulang@uniontech.com
Signed-off-by: Lang Xu 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: Allow instructions with arena source and non-arena dest registers

2026-05-23T11:04:25+00:00

[ Upstream commit ac61bffe91d4bda08806e12957c6d64756d042db ]

The compiler sometimes stores the result of a PTR_TO_ARENA and SCALAR
operation into the scalar register rather than the pointer register.
Relax the verifier to allow operations between a source arena register
and a destination non-arena register, marking the destination's value
as a PTR_TO_ARENA.

Signed-off-by: Emil Tsalapatis 
Acked-by: Song Liu 
Fixes: 6082b6c328b5 ("bpf: Recognize addr_space_cast instruction in the verifier.")
Link: https://lore.kernel.org/r/20260412174546.18684-2-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars

2026-05-23T11:04:24+00:00

[ Upstream commit 2f2ec8e7730e21fc9bd49e0de9cdd58213ea24d0 ]

When regsafe() compares two scalar registers that both carry
BPF_ADD_CONST, check_scalar_ids() maps their full compound id
(aka base | BPF_ADD_CONST flag) as one idmap entry. However,
it never verifies that the underlying base ids, that is, with
the flag stripped are consistent with existing idmap mappings.

This allows construction of two verifier states where the old
state has R3 = R2 + 10 (both sharing base id A) while the current
state has R3 = R4 + 10 (base id C, unrelated to R2). The idmap
creates two independent entries: A->B (for R2) and A|flag->C|flag
(for R3), without catching that A->C conflicts with A->B. State
pruning then incorrectly succeeds.

Fix this by additionally verifying base ID mapping consistency
whenever BPF_ADD_CONST is set: after mapping the compound ids,
also invoke check_ids() on the base IDs (flag bits stripped).
This ensures that if A was already mapped to B from comparing
the source register, any ADD_CONST derivative must also derive
from B, not an unrelated C.

Fixes: 98d7ca374ba4 ("bpf: Track delta between "linked" registers.")
Reported-by: STAR Labs SG 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/r/20260410232651.559778-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: Relax scalar id equivalence for state pruning

2026-05-23T11:04:24+00:00

[ Upstream commit b0388bafa4949bd30af7b3be5ee415f2a25ac014 ]

Scalar register IDs are used by the verifier to track relationships
between registers and enable bounds propagation across those
relationships. Once an ID becomes singular (i.e. only a single
register/stack slot carries it), it can no longer contribute to bounds
propagation and effectively becomes stale. The previous commit makes the
verifier clear such ids before caching the state.

When comparing the current and cached states for pruning, these stale
IDs can cause technically equivalent states to be considered different
and thus prevent pruning.

For example, in the selftest added in the next commit, two registers -
r6 and r7 are not linked to any other registers and get cached with
id=0, in the current state, they are both linked to each other with
id=A.  Before this commit, check_scalar_ids would give temporary ids to
r6 and r7 (say tid1 and tid2) and then check_ids() would map tid1->A,
and when it would see tid2->A, it would not consider these state
equivalent.

Relax scalar ID equivalence by treating rold->id == 0 as "independent":
if the old state did not rely on any ID relationships for a register,
then any ID/linking present in the current state only adds constraints
and is always safe to accept for pruning. Implement this by returning
true immediately in check_scalar_ids() when old_id == 0.

Maintain correctness for the opposite direction (old_id != 0 && cur_id
== 0) by still allocating a temporary ID for cur_id == 0. This avoids
incorrectly allowing multiple independent current registers (id==0) to
satisfy a single linked old ID during mapping.

Signed-off-by: Puranjay Mohan 
Link: https://lore.kernel.org/r/20260203165102.2302462-5-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov 
Stable-dep-of: 2f2ec8e7730e ("bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars")
Signed-off-by: Sasha Levin

bpf: Fix RCU stall in bpf_fd_array_map_clear()

2026-05-23T11:04:24+00:00

[ Upstream commit 4406942e65ca128c56c67443832988873c21d2e9 ]

Add a missing cond_resched() in bpf_fd_array_map_clear() loop.

For PROG_ARRAY maps with many entries this loop calls
prog_array_map_poke_run() per entry which can be expensive, and
without yielding this can cause RCU stalls under load:

  rcu: Stack dump where RCU GP kthread last ran:
  CPU: 0 UID: 0 PID: 30932 Comm: kworker/0:2 Not tainted 6.14.0-13195-g967e8def1100 #2 PREEMPT(undef)
  Workqueue: events prog_array_map_clear_deferred
  RIP: 0010:write_comp_data+0x38/0x90 kernel/kcov.c:246
  Call Trace:
   
   prog_array_map_poke_run+0x77/0x380 kernel/bpf/arraymap.c:1096
   __fd_array_map_delete_elem+0x197/0x310 kernel/bpf/arraymap.c:925
   bpf_fd_array_map_clear kernel/bpf/arraymap.c:1000 [inline]
   prog_array_map_clear_deferred+0x119/0x1b0 kernel/bpf/arraymap.c:1141
   process_one_work+0x898/0x19d0 kernel/workqueue.c:3238
   process_scheduled_works kernel/workqueue.c:3319 [inline]
   worker_thread+0x770/0x10b0 kernel/workqueue.c:3400
   kthread+0x465/0x880 kernel/kthread.c:464
   ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:153
   ret_from_fork_asm+0x19/0x30 arch/x86/entry/entry_64.S:245
   

Reviewed-by: Sun Jian 
Fixes: da765a2f5993 ("bpf: Add poke dependency tracking for prog array maps")
Signed-off-by: Sechang Lim 
Link: https://lore.kernel.org/r/20260407103823.3942156-1-rhkrqnwk98@gmail.com
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin