{"id":"CVE-2026-64435","summary":"audit: Fix data races of skb_queue_len() readers on audit_queue","details":"In the Linux kernel, the following vulnerability has been resolved:\n\naudit: Fix data races of skb_queue_len() readers on audit_queue\n\nMultiple readers access audit_queue.qlen via skb_queue_len() without\nholding the queue lock or using READ_ONCE(), while kauditd writes to\nthis field via the skb_dequeue() → __skb_unlink() path with WRITE_ONCE()\nprotected by a spinlock. This constitutes data races.\n\nAll affected skb_queue_len(&audit_queue) call sites:\n  - kauditd_thread() wait_event_freezable() condition\n  - audit_receive_msg() AUDIT_GET handler (s.backlog assignment)\n  - audit_receive() backlog check\n  - audit_log_start() backlog check and pr_warn()\n\nKCSAN reports the following conflicting access pattern (one example):\n==================================================================\nBUG: KCSAN: data-race in audit_log_start / skb_dequeue\n\nwrite (marked) to 0xffffffff8512ee20 of 4 bytes by task 661 on cpu 57:\n skb_dequeue+0x70/0xf0\n kauditd_send_queue+0x71/0x220\n kauditd_thread+0x1cb/0x430\n kthread+0x1c2/0x210\n ret_from_fork+0x162/0x1a0\n ret_from_fork_asm+0x1a/0x30\n\nread to 0xffffffff8512ee20 of 4 bytes by task 36586 on cpu 1:\n audit_log_start+0x2a0/0x6b0\n audit_core_dumps+0x64/0xa0\n do_coredump+0x14b/0x1260\n get_signal+0xeb2/0xf70\n arch_do_signal_or_restart+0x41/0x170\n exit_to_user_mode_loop+0xa2/0x1c0\n do_syscall_64+0x1a3/0x1c0\n entry_SYSCALL_64_after_hwframe+0x76/0xe0\n\nvalue changed: 0x00000001 -\u003e 0x00000000\n==================================================================\n\nResolve the race by switching to lockless helper skb_queue_len_lockless(),\nwhich internally uses READ_ONCE() and properly pairs with the WRITE_ONCE()\nwrite accesses already present on the writer side.\n\n[PM: line length tweak]","modified":"2026-07-28T04:02:54.418626296Z","published":"2026-07-25T08:51:09.688Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64435.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/69f98fff30bdaa72b0cb0e7e078ab6456a0a59b0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7ff42312ccde549f8c698723822c7db35107a39b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a3d85dec60bb0622360fc176b2a51abdbe2ff0ad"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b35597bdae1a5d8395da4b9baa993b9b71f74d68"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c5186201fa7030289cc4fe23fae87a3fcb566856"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c9a71daaecb2fb1d8c704545cc0b1c920b9bf5d7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e575dabb805252e3113fdc3f56f6ecacfde422d0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fe997a84a385f840b593ead92e575503a5046cee"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64435.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64435"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3197542482df22c2a131d4a813280bd7c54cedf5"},{"fixed":"69f98fff30bdaa72b0cb0e7e078ab6456a0a59b0"},{"fixed":"b35597bdae1a5d8395da4b9baa993b9b71f74d68"},{"fixed":"e575dabb805252e3113fdc3f56f6ecacfde422d0"},{"fixed":"7ff42312ccde549f8c698723822c7db35107a39b"},{"fixed":"a3d85dec60bb0622360fc176b2a51abdbe2ff0ad"},{"fixed":"fe997a84a385f840b593ead92e575503a5046cee"},{"fixed":"c5186201fa7030289cc4fe23fae87a3fcb566856"},{"fixed":"c9a71daaecb2fb1d8c704545cc0b1c920b9bf5d7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64435.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.10.0"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64435.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H"}]}