GHSA-4W7W-2MRJ-36VW
Vulnerability from github – Published: 2026-06-25 09:31 – Updated: 2026-06-25 09:31In 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().
{
"affected": [],
"aliases": [
"CVE-2026-53163"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-25T09:16:33Z",
"severity": null
},
"details": "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": "GHSA-4w7w-2mrj-36vw",
"modified": "2026-06-25T09:31:19Z",
"published": "2026-06-25T09:31:19Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53163"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/40a25d59e85b3c8709ac2424d44f65610467871e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/55363fa0a04524d11efeaadee734d2db1756ed27"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a388e3dfaf9538a680de5ed43a8ebb5dd45b6e53"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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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.