CVE-2025-21767
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context
The following bug report happened with a PREEMPT_RT kernel:
It is due to the fact that clocksource_verify_choose_cpus() is invoked with preemption disabled. This function invokes get_random_u32() to obtain random numbers for choosing CPUs. The batched_entropy_32 local lock and/or the base_crng.lock spinlock in driver/char/random.c will be acquired during the call. In PREEMPT_RT kernel, they are both sleeping locks and so cannot be acquired in atomic context.
Leer descripción completaMostrar menos
Fix this problem by using migrate_disable() to allow smp_processor_id() to be reliably used without introducing atomic context. preempt_disable() is then called after clocksource_verify_choose_cpus() but before the clocksource measurement is being run to avoid introducing unexpected latency.
Detalles técnicos trazas, registros y código del informe original
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 get_random_u32+0x4f/0x110 clocksource_verify_choose_cpus+0xab/0x1a0 clocksource_verify_percpu.part.0+0x6b/0x330 clocksource_watchdog_kthread+0x193/0x1a0
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: 0.18%
- Percentil entre todas las CVEs puntuadas: 7
- 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
- CWE-667
Referencias
- https://git.kernel.org/stable/c/0fb534187d2355f6c8f995321e76d1ccd1262ac1
- https://git.kernel.org/stable/c/60f54f0d4ea530950549a8263e6fdd70a40490a4
- https://git.kernel.org/stable/c/6bb05a33337b2c842373857b63de5c9bf1ae2a09
- https://git.kernel.org/stable/c/852805b6cbdb69c298a8fc9fbe79994c95106e04
- https://git.kernel.org/stable/c/8783ceeee797d9aa9cfe150690fb9d0bac8cc459
- https://git.kernel.org/stable/c/cc3d79e7c806cb57d71c28a4a35e7d7fb3265faa
- https://git.kernel.org/stable/c/d9c217fadfcff7a8df58567517d1e4253f3fd243
- https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.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\nclocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context\n\nThe following bug report happened with a PREEMPT_RT kernel:\n\n BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48\n in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog\n preempt_count: 1, expected: 0\n RCU nest depth: 0, expected: 0\n get_random_u32+0x4f/0x110\n clocksource_verify_choose_cpus+0xab/0x1a0\n clocksource_verify_percpu.part.0+0x6b/0x330\n clocksource_watchdog_kthread+0x193/0x1a0\n\nIt is due to the fact that clocksource_verify_choose_cpus() is invoked with\npreemption disabled. This function invokes get_random_u32() to obtain\nrandom numbers for choosing CPUs. The batched_entropy_32 local lock and/or\nthe base_crng.lock spinlock in driver/char/random.c will be acquired during\nthe call. In PREEMPT_RT kernel, they are both sleeping locks and so cannot\nbe acquired in atomic context.\n\nFix this problem by using migrate_disable() to allow smp_processor_id() to\nbe reliably used without introducing atomic context. preempt_disable() is\nthen called after clocksource_verify_choose_cpus() but before the\nclocksource measurement is being run to avoid introducing unexpected\nlatency."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: clocksource: Use migrants_disable() para evitar llamar a get_random_u32() en un contexto atómico El siguiente informe de error ocurrió con un kernel PREEMPT_RT: ERROR: función inactiva llamada desde un contexto no válido en kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog preempt_count: 1, expected: 0 Profundidad de anidamiento de RCU: 0, expected: 0 get_random_u32+0x4f/0x110 clocksource_verify_choose_cpus+0xab/0x1a0 clocksource_verify_percpu.part.0+0x6b/0x330 clocksource_watchdog_kthread+0x193/0x1a0 Esto se debe al hecho de que clocksource_verify_choose_cpus() se invoca con la preempción deshabilitada. Esta función invoca get_random_u32() para obtener números aleatorios para elegir las CPU. El bloqueo local batched_entropy_32 y/o el spinlock base_crng.lock en driver/char/random.c se adquirirán durante la llamada. En el kernel PREEMPT_RT, ambos son bloqueos inactivos y, por lo tanto, no se pueden adquirir en un contexto atómico. Solucione este problema utilizando migrants_disable() para permitir que smp_processor_id() se utilice de manera confiable sin introducir un contexto atómico. Luego, se llama a preempt_disable() después de clocksource_verify_choose_cpus() pero antes de que se ejecute la medición de la fuente de reloj para evitar introducir una latencia inesperada."
}
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"lastModified": "2026-06-17T08:44:13.860",
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