audit: Fix data races of skb_queue_len() readers on audit_queue

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-64435
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-25 10:17:27 UTC
Updated2026-07-27 05:16:49 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: audit: Fix data races of skb_queue_len() readers on audit_queue 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. [PM: line length tweak]

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS: 0.004240000 probability, percentile 0.347660000 (date 2026-07-27)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
3.1CNADECLARED8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 3197542482df22c2a131d4a813280bd7c54cedf5 69f98fff30bdaa72b0cb0e7e078ab6456a0a59b0 git Not specified
CNA Linux Linux affected 3197542482df22c2a131d4a813280bd7c54cedf5 b35597bdae1a5d8395da4b9baa993b9b71f74d68 git Not specified
CNA Linux Linux affected 3197542482df22c2a131d4a813280bd7c54cedf5 e575dabb805252e3113fdc3f56f6ecacfde422d0 git Not specified
CNA Linux Linux affected 3197542482df22c2a131d4a813280bd7c54cedf5 7ff42312ccde549f8c698723822c7db35107a39b git Not specified
CNA Linux Linux affected 3197542482df22c2a131d4a813280bd7c54cedf5 a3d85dec60bb0622360fc176b2a51abdbe2ff0ad git Not specified
CNA Linux Linux affected 3197542482df22c2a131d4a813280bd7c54cedf5 fe997a84a385f840b593ead92e575503a5046cee git Not specified
CNA Linux Linux affected 3197542482df22c2a131d4a813280bd7c54cedf5 c5186201fa7030289cc4fe23fae87a3fcb566856 git Not specified
CNA Linux Linux affected 3197542482df22c2a131d4a813280bd7c54cedf5 c9a71daaecb2fb1d8c704545cc0b1c920b9bf5d7 git Not specified
CNA Linux Linux affected 4.10 Not specified
CNA Linux Linux unaffected 4.10 semver Not specified
CNA Linux Linux unaffected 5.10.261 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.212 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.96 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.39 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.4 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/7ff42312ccde549f8c698723822c7db35107a39b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c5186201fa7030289cc4fe23fae87a3fcb566856 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e575dabb805252e3113fdc3f56f6ecacfde422d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/69f98fff30bdaa72b0cb0e7e078ab6456a0a59b0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fe997a84a385f840b593ead92e575503a5046cee 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c9a71daaecb2fb1d8c704545cc0b1c920b9bf5d7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a3d85dec60bb0622360fc176b2a51abdbe2ff0ad 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b35597bdae1a5d8395da4b9baa993b9b71f74d68 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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