CVE-2022-50103
In the Linux kernel, the following vulnerability has been resolved:
sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed
With cgroup v2, the cpuset's cpus_allowed mask can be empty indicating that the cpuset will just use the effective CPUs of its parent. So cpuset_can_attach() can call task_can_attach() with an empty mask. This can lead to cpumask_any_and() returns nr_cpu_ids causing the call to dl_bw_of() to crash due to percpu value access of an out of bound CPU value. For example:
Fix that by using effective_cpus instead. For cgroup v1, effective_cpus is the same as cpus_allowed. For v2, effective_cpus is the real cpumask to be used by tasks within the cpuset anyway.
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Also update task_can_attach()'s 2nd argument name to cs_effective_cpus to reflect the change. In addition, a check is added to task_can_attach() to guard against the possibility that cpumask_any_and() may return a value >= nr_cpu_ids.
Detalles técnicos trazas, registros y código del informe original
[80468.182258] BUG: unable to handle page fault for address: ffffffff8b6648b0 : [80468.191019] RIP: 0010:dl_cpu_busy+0x30/0x2b0 : [80468.207946] Call Trace: [80468.208947] cpuset_can_attach+0xa0/0x140 [80468.209953] cgroup_migrate_execute+0x8c/0x490 [80468.210931] cgroup_update_dfl_csses+0x254/0x270 [80468.211898] cgroup_subtree_control_write+0x322/0x400 [80468.212854] kernfs_fop_write_iter+0x11c/0x1b0 [80468.213777] new_sync_write+0x11f/0x1b0 [80468.214689] vfs_write+0x1eb/0x280 [80468.215592] ksys_write+0x5f/0xe0 [80468.216463] do_syscall_64+0x5c/0x80 [80468.224287] entry_SYSCALL_64_after_hwframe+0x44/0xae
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- Puntuación base: 7.1
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.19%
- Percentil entre todas las CVEs puntuadas: 8
- 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).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1499.004Application or System Exploitationimpact80 %
Vulnerabilidad local (AV:L) sin interacción de usuario que causa panic en el kernel por acceso a memoria fuera de límites (CWE-125: Out-of-bounds Read), resultando en denegación de servicio.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- CWE-125
Referencias
- https://git.kernel.org/stable/c/147f66d22f58712dce7ccdd6a1f6cb3ee8042df4
- https://git.kernel.org/stable/c/336626564b58071b8980a4e6a31a8f5d92705d9b
- https://git.kernel.org/stable/c/357f3f0e522a6ce1ce4a571cb780d9861d53bec7
- https://git.kernel.org/stable/c/b6e8d40d43ae4dec00c8fea2593eeea3114b8f44
- https://git.kernel.org/stable/c/f56607b44c9896e51678a7e8cdd3a5479f4b4548
JSON original (NVD)
Mostrar
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed\n\nWith cgroup v2, the cpuset's cpus_allowed mask can be empty indicating\nthat the cpuset will just use the effective CPUs of its parent. So\ncpuset_can_attach() can call task_can_attach() with an empty mask.\nThis can lead to cpumask_any_and() returns nr_cpu_ids causing the call\nto dl_bw_of() to crash due to percpu value access of an out of bound\nCPU value. For example:\n\n\t[80468.182258] BUG: unable to handle page fault for address: ffffffff8b6648b0\n\t :\n\t[80468.191019] RIP: 0010:dl_cpu_busy+0x30/0x2b0\n\t :\n\t[80468.207946] Call Trace:\n\t[80468.208947] cpuset_can_attach+0xa0/0x140\n\t[80468.209953] cgroup_migrate_execute+0x8c/0x490\n\t[80468.210931] cgroup_update_dfl_csses+0x254/0x270\n\t[80468.211898] cgroup_subtree_control_write+0x322/0x400\n\t[80468.212854] kernfs_fop_write_iter+0x11c/0x1b0\n\t[80468.213777] new_sync_write+0x11f/0x1b0\n\t[80468.214689] vfs_write+0x1eb/0x280\n\t[80468.215592] ksys_write+0x5f/0xe0\n\t[80468.216463] do_syscall_64+0x5c/0x80\n\t[80468.224287] entry_SYSCALL_64_after_hwframe+0x44/0xae\n\nFix that by using effective_cpus instead. For cgroup v1, effective_cpus\nis the same as cpus_allowed. For v2, effective_cpus is the real cpumask\nto be used by tasks within the cpuset anyway.\n\nAlso update task_can_attach()'s 2nd argument name to cs_effective_cpus to\nreflect the change. In addition, a check is added to task_can_attach()\nto guard against the possibility that cpumask_any_and() may return a\nvalue >= nr_cpu_ids."
},
{
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"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: sched, cpuset: Se solucionó el pánico de dl_cpu_busy() debido a un valor de cs->cpus_allowed vacío. Con cgroup v2, la máscara cpus_allowed de cpuset puede estar vacía, lo que indica que solo usará las CPU efectivas de su padre. Por lo tanto, cpuset_can_attach() puede llamar a task_can_attach() con una máscara vacía. Esto puede provocar que cpumask_any_and() devuelva nr_cpu_ids, lo que provoca el bloqueo de la llamada a dl_bw_of() debido al acceso a un valor de CPU fuera de los límites. Por ejemplo: [80468.182258] ERROR: no se puede manejar el error de página para la dirección: ffffffff8b6648b0 : [80468.191019] RIP: 0010:dl_cpu_busy+0x30/0x2b0 : [80468.207946] Rastreo de llamadas: [80468.208947] cpuset_can_attach+0xa0/0x140 [80468.209953] cgroup_migrate_execute+0x8c/0x490 [80468.210931] cgroup_update_dfl_csses+0x254/0x270 [80468.211898] Solucione esto utilizando effective_cpus en su lugar. Para cgroup v1, effective_cpus es igual que cpus_allowed. Para v2, effective_cpus es la máscara de CPU real que usarán las tareas dentro del conjunto de CPU. Actualice también el segundo argumento de task_can_attach() a cs_effective_cpus para reflejar el cambio. Además, se ha añadido una comprobación a task_can_attach() para evitar que cpumask_any_and() devuelva un valor mayor que nr_cpu_ids."
}
],
"lastModified": "2026-06-17T05:22:46.027",
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