FKIE_CVE-2026-53163
Vulnerability from fkie_nvd - Published: 2026-06-25 09:16 - Updated: 2026-06-30 14:44
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
locking/rtmutex: Skip remove_waiter() when waiter is not enqueued
syzbot triggered the following splat in remove_waiter() via
FUTEX_CMP_REQUEUE_PI:
KASAN: null-ptr-deref in range [0x0000000000000a88-0x0000000000000a8f]
class_raw_spinlock_constructor
remove_waiter+0x159/0x1200 kernel/locking/rtmutex.c:1561
rt_mutex_start_proxy_lock+0x103/0x120
futex_requeue+0x10e4/0x20d0
__x64_sys_futex+0x34f/0x4d0
task_blocks_on_rt_mutex() does not arm the waiter upon deadlock detection,
leaving waiter->task nil, where 3bfdc63936dd ("rtmutex: Use waiter::task instead
of current in remove_waiter()") made this fatal.
Furthermore, rt_mutex_start_proxy_lock() should not be calling into remove_waiter()
upon a successfully grabbing the rtmutex. 1a1fb985f2e2 ("futex: Handle early deadlock
return correctly"), moved the remove_waiter() out of __rt_mutex_start_proxy_lock()
(where 'ret' was only ever 0 or < 0) into the wrapper. Tighten this check to
account for try_to_take_rt_mutex().
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"kernel/locking/rtmutex.c",
"kernel/locking/rtmutex_api.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "a388e3dfaf9538a680de5ed43a8ebb5dd45b6e53",
"status": "affected",
"version": "3fb7394a837740770f0d6b4b30567e60786a63f2",
"versionType": "git"
},
{
"lessThan": "55363fa0a04524d11efeaadee734d2db1756ed27",
"status": "affected",
"version": "88614876370aac8ad1050ad785a4c095ba17ac11",
"versionType": "git"
},
{
"lessThan": "40a25d59e85b3c8709ac2424d44f65610467871e",
"status": "affected",
"version": "3bfdc63936dd4773109b7b8c280c0f3b5ae7d349",
"versionType": "git"
},
{
"status": "affected",
"version": "d8cce4773c2b23d819baf5abedc62f7b430e8745",
"versionType": "git"
},
{
"status": "affected",
"version": "8a1fc8d698ac5e5916e3082a0f74450d71f9611f",
"versionType": "git"
},
{
"status": "affected",
"version": "6d52dfcb2a5db86e346cf51f8fcf2071b8085166",
"versionType": "git"
},
{
"lessThan": "6.2",
"status": "affected",
"version": "6.1.175",
"versionType": "semver"
},
{
"lessThan": "6.7",
"status": "affected",
"version": "6.6.140",
"versionType": "semver"
},
{
"lessThan": "6.13",
"status": "affected",
"version": "6.12.86",
"versionType": "semver"
}
]
},
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"kernel/locking/rtmutex.c",
"kernel/locking/rtmutex_api.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "6.18.36",
"status": "affected",
"version": "6.18.27",
"versionType": "semver"
},
{
"lessThan": "7.0.13",
"status": "affected",
"version": "7.0.4",
"versionType": "semver"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlocking/rtmutex: Skip remove_waiter() when waiter is not enqueued\n\nsyzbot triggered the following splat in remove_waiter() via\nFUTEX_CMP_REQUEUE_PI:\n\n KASAN: null-ptr-deref in range [0x0000000000000a88-0x0000000000000a8f]\n class_raw_spinlock_constructor\n remove_waiter+0x159/0x1200 kernel/locking/rtmutex.c:1561\n rt_mutex_start_proxy_lock+0x103/0x120\n futex_requeue+0x10e4/0x20d0\n __x64_sys_futex+0x34f/0x4d0\n\ntask_blocks_on_rt_mutex() does not arm the waiter upon deadlock detection,\nleaving waiter-\u003etask nil, where 3bfdc63936dd (\"rtmutex: Use waiter::task instead\nof current in remove_waiter()\") made this fatal.\n\nFurthermore, rt_mutex_start_proxy_lock() should not be calling into remove_waiter()\nupon a successfully grabbing the rtmutex. 1a1fb985f2e2 (\"futex: Handle early deadlock\nreturn correctly\"), moved the remove_waiter() out of __rt_mutex_start_proxy_lock()\n(where \u0027ret\u0027 was only ever 0 or \u003c 0) into the wrapper. Tighten this check to\naccount for try_to_take_rt_mutex()."
}
],
"id": "CVE-2026-53163",
"lastModified": "2026-06-30T14:44:27.313",
"metrics": {},
"published": "2026-06-25T09:16:33.703",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/40a25d59e85b3c8709ac2424d44f65610467871e"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/55363fa0a04524d11efeaadee734d2db1756ed27"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a388e3dfaf9538a680de5ed43a8ebb5dd45b6e53"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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