{"id":"CVE-2026-99179","revision":"8909774046764efd83f3e740304a86dc","records":[{"revision":"8909774046764efd83f3e740304a86dc","observedAt":"2026-10-28T11:27:43.363+00:00","statement":{"source":"cve-program","id":"CVE-2026-99179","aliases":[],"title":"watch_queue: Fix note pool publication race in watch_queue_set_size()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nwatch_queue: Fix note pool publication race in watch_queue_set_size()\n\nThere is a race between watch_queue_set_size() and post_one_notification().\nwatch_queue_set_size() publishes wqueue->notes, notes_bitmap, nr_pages and\nnr_notes with plain stores, and post_one_notification() reads them with\nplain loads under a different lock, so nothing orders the four stores\nagainst the poster's loads: depending on the build, notes can be stored\nlast (gcc 14 on x86-64 does this).  Since keyctl_watch_key() lets a watch\nattach to a queue before it is sized, post_one_notification() can already\nbe running on another CPU at that moment: it reads nr_notes > 0, passes\nits bounds check, and then reads notes while it is still NULL,\ndereferencing notes[0].\n\nAn unprivileged user triggers this reliably by watching one of its own\nkeys through a notification pipe and racing ioctl(IOC_WATCH_QUEUE_SET_SIZE)\non that pipe against keyctl(KEYCTL_SETPERM) on the key from another CPU,\ntriggering:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000000\n  RIP: 0010:post_one_notification.isra.0+0xa2/0x1e0\n  Call Trace:\n   __post_watch_notification+0x148/0x180\n   keyctl_setperm_key+0x119/0x130\n   do_syscall_64+0x108/0x4c0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nFix this by publishing nr_notes last with smp_store_release(), and by\nreading it once with smp_load_acquire() in post_one_notification() before\nthe bitmap and the page array are touched.  A poster that observes a\nnon-zero nr_notes then also observes the pool behind it; one that observes\nzero drops the notification as before.","state":0,"publishedAt":"2026-10-28T10:35:32.734+00:00","modifiedAt":"2026-10-28T10:35:32.734+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/watch_queue.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"c73be61cede5882f9605a852414db559c0ebedfd\",\n                            \"lessThan\": \"811fb6d0b07605e8e8d93bde8748be4b3028809a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"c73be61cede5882f9605a852414db559c0ebedfd\",\n                            \"lessThan\": \"9e73a6754457ffed8399b835552013b9363e51d1\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"c73be61cede5882f9605a852414db559c0ebedfd\",\n                            \"lessThan\": \"5e531d62f1f8834faf7a4eed0d41105cf6570a8f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/watch_queue.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"5.8\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"5.8\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.59\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.13\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/811fb6d0b07605e8e8d93bde8748be4b3028809a","https://git.kernel.org/stable/c/9e73a6754457ffed8399b835552013b9363e51d1","https://git.kernel.org/stable/c/5e531d62f1f8834faf7a4eed0d41105cf6570a8f"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99179","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-99179","identifiers":["CVE-2026-99179"]},"retained":false,"historicalAffected":[]}],"coverage":[]}