CVE-2026-31555
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
futex: Clear stale exiting pointer in futex_lock_pi() retry path
Fuzzying/stressing futexes triggered:
When futex_lock_pi_atomic() sees the owner is exiting, it returns -EBUSY and stores a refcounted task pointer in 'exiting'.
After wait_for_owner_exiting() consumes that reference, the local pointer is never reset to nil. Upon a retry, if futex_lock_pi_atomic() returns a different error, the bogus pointer is passed to wait_for_owner_exiting().
CPU0 CPU1 CPU2 futex_lock_pi(uaddr) // acquires the PI futex exit() futex_cleanup_begin() futex_state = EXITING; futex_lock_pi(uaddr) futex_lock_pi_atomic() attach_to_pi_owner() // observes EXITING *exiting = owner; // takes ref return -EBUSY wait_for_owner_exiting(-EBUSY, owner) put_task_struct(); // drops ref // exiting still points to owner goto retry; futex_lock_pi_atomic() lock_pi_update_atomic() cmpxchg(uaddr) *uaddr ^= WAITERS // whatever // value changed return -EAGAIN; wait_for_owner_exiting(-EAGAIN, exiting) // stale WARN_ON_ONCE(exiting)
Leer descripción completaMostrar menos
Fix this by resetting upon retry, essentially aligning it with requeue_pi.
Detalles técnicos trazas, registros y código del informe original
WARNING: kernel/futex/core.c:825 at wait_for_owner_exiting+0x7a/0x80, CPU#11: futex_lock_pi_s/524
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.17%
- Percentil entre todas las CVEs puntuadas: 6
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- NVD-CWE-noinfo
Referencias
- https://git.kernel.org/stable/c/210d36d892de5195e6766c45519dfb1e65f3eb83
- https://git.kernel.org/stable/c/33095ae3bdde5e5c264d7e88a2f3e7703a26c7aa
- https://git.kernel.org/stable/c/5e8e06bf8909e79b4acd950cf578cfc2f10bbefa
- https://git.kernel.org/stable/c/71112e62807d1925dc3ae6188b11f8cfc85aec23
- https://git.kernel.org/stable/c/7475dfad10a05a5bfadebf5f2499bd61b19ed293
- https://git.kernel.org/stable/c/92e47ad03e03dbb5515bdf06444bf6b1e147310d
- https://git.kernel.org/stable/c/de7c0c04ad868f2cee6671b11c0a6d20421af1da
- https://git.kernel.org/stable/c/e7824ec168d2ac883a213cd1f4d6cc0816002a85
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Clear stale exiting pointer in futex_lock_pi() retry path\n\nFuzzying/stressing futexes triggered:\n\n WARNING: kernel/futex/core.c:825 at wait_for_owner_exiting+0x7a/0x80, CPU#11: futex_lock_pi_s/524\n\nWhen futex_lock_pi_atomic() sees the owner is exiting, it returns -EBUSY\nand stores a refcounted task pointer in 'exiting'.\n\nAfter wait_for_owner_exiting() consumes that reference, the local pointer\nis never reset to nil. Upon a retry, if futex_lock_pi_atomic() returns a\ndifferent error, the bogus pointer is passed to wait_for_owner_exiting().\n\n CPU0\t\t\t CPU1\t\t CPU2\n futex_lock_pi(uaddr)\n // acquires the PI futex\n exit()\n futex_cleanup_begin()\n futex_state = EXITING;\n\t\t\t futex_lock_pi(uaddr)\n\t\t\t futex_lock_pi_atomic()\n\t\t\t\t attach_to_pi_owner()\n\t\t\t\t // observes EXITING\n\t\t\t\t *exiting = owner; // takes ref\n\t\t\t\t return -EBUSY\n\t\t\t wait_for_owner_exiting(-EBUSY, owner)\n\t\t\t\t put_task_struct(); // drops ref\n\t\t\t // exiting still points to owner\n\t\t\t goto retry;\n\t\t\t futex_lock_pi_atomic()\n\t\t\t\t lock_pi_update_atomic()\n\t\t\t\t cmpxchg(uaddr)\n\t\t\t\t\t*uaddr ^= WAITERS // whatever\n\t\t\t\t // value changed\n\t\t\t\t return -EAGAIN;\n\t\t\t wait_for_owner_exiting(-EAGAIN, exiting) // stale\n\t\t\t\t WARN_ON_ONCE(exiting)\n\nFix this by resetting upon retry, essentially aligning it with requeue_pi."
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