CVE-2026-99179
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: watch_queue: Fix note pool publication race in watch_queue_set_size() There is a race between watch_queue_set_size() and post_one_notification(). watch_queue_set_size() publishes wqueue->notes, notes_bitmap, nr_pages and nr_notes with plain stores, and post_one_notification() reads them with plain loads under a different lock, so nothing orders the four stores against the poster's loads: depending on the build, notes can be stored last (gcc 14 on x86-64 does this). Since keyctl_watch_key() lets a watch attach to a queue before it is sized, post_one_notification() can already be running on another CPU at that moment: it reads nr_notes > 0, passes its bounds check, and then reads notes while it is still NULL, dereferencing notes[0]. An unprivileged user triggers this reliably by watching one of its own keys through a notification pipe and racing ioctl(IOC_WATCH_QUEUE_SET_SIZE) on that pipe against keyctl(KEYCTL_SETPERM) on the key from another CPU, triggering: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:post_one_notification.isra.0+0xa2/0x1e0 Call Trace: __post_watch_notification+0x148/0x180 keyctl_setperm_key+0x119/0x130 do_syscall_64+0x108/0x4c0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Kernel panic - not syncing: Fatal exception in interrupt Fix this by publishing nr_notes last with smp_store_release(), and by reading it once with smp_load_acquire() in post_one_notification() before the bitmap and the page array are touched. A poster that observes a non-zero nr_notes then also observes the pool behind it; one that observes zero drops the notification as before.
View original CVE JSON
{
"id": "CVE-2026-99179",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-10-28T11:17:38.633",
"lastModified": "2026-10-28T11:17:38.633",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"kernel/watch_queue.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "c73be61cede5882f9605a852414db559c0ebedfd",
"lessThan": "811fb6d0b07605e8e8d93bde8748be4b3028809a",
"versionType": "git",
"status": "affected"
},
{
"version": "c73be61cede5882f9605a852414db559c0ebedfd",
"lessThan": "9e73a6754457ffed8399b835552013b9363e51d1",
"versionType": "git",
"status": "affected"
},
{
"version": "c73be61cede5882f9605a852414db559c0ebedfd",
"lessThan": "5e531d62f1f8834faf7a4eed0d41105cf6570a8f",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"kernel/watch_queue.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "5.8",
"status": "affected"
},
{
"version": "0",
"lessThan": "5.8",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.59",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.13",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/5e531d62f1f8834faf7a4eed0d41105cf6570a8f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/811fb6d0b07605e8e8d93bde8748be4b3028809a",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9e73a6754457ffed8399b835552013b9363e51d1",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}