CVE-2025-21771
Estado: AnalizadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix incorrect autogroup migration detection
scx_move_task() is called from sched_move_task() and tells the BPF scheduler that cgroup migration is being committed. sched_move_task() is used by both cgroup and autogroup migrations and scx_move_task() tried to filter out autogroup migrations by testing the destination cgroup and PF_EXITING but this is not enough. In fact, without explicitly tagging the thread which is doing the cgroup migration, there is no good way to tell apart scx_move_task() invocations for racing migration to the root cgroup and an autogroup migration.
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This led to scx_move_task() incorrectly ignoring a migration from non-root cgroup to an autogroup of the root cgroup triggering the following warning:
Fix it by adding an argument to sched_move_task() that indicates whether the moving is for a cgroup or autogroup migration. After the change, scx_move_task() is called only for cgroup migrations and renamed to scx_cgroup_move_task().
Detalles técnicos trazas, registros y código del informe original
WARNING: CPU: 7 PID: 1 at kernel/sched/ext.c:3725 scx_cgroup_can_attach+0x196/0x340
...
Call Trace:
<TASK>
cgroup_migrate_execute+0x5b1/0x700
cgroup_attach_task+0x296/0x400
__cgroup_procs_write+0x128/0x140
cgroup_procs_write+0x17/0x30
kernfs_fop_write_iter+0x141/0x1f0
vfs_write+0x31d/0x4a0
__x64_sys_write+0x72/0xf0
do_syscall_64+0x82/0x160
entry_SYSCALL_64_after_hwframe+0x76/0x7eCVSS
- 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: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- 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
JSON original (NVD)
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix incorrect autogroup migration detection\n\nscx_move_task() is called from sched_move_task() and tells the BPF scheduler\nthat cgroup migration is being committed. sched_move_task() is used by both\ncgroup and autogroup migrations and scx_move_task() tried to filter out\nautogroup migrations by testing the destination cgroup and PF_EXITING but\nthis is not enough. In fact, without explicitly tagging the thread which is\ndoing the cgroup migration, there is no good way to tell apart\nscx_move_task() invocations for racing migration to the root cgroup and an\nautogroup migration.\n\nThis led to scx_move_task() incorrectly ignoring a migration from non-root\ncgroup to an autogroup of the root cgroup triggering the following warning:\n\n WARNING: CPU: 7 PID: 1 at kernel/sched/ext.c:3725 scx_cgroup_can_attach+0x196/0x340\n ...\n Call Trace:\n <TASK>\n cgroup_migrate_execute+0x5b1/0x700\n cgroup_attach_task+0x296/0x400\n __cgroup_procs_write+0x128/0x140\n cgroup_procs_write+0x17/0x30\n kernfs_fop_write_iter+0x141/0x1f0\n vfs_write+0x31d/0x4a0\n __x64_sys_write+0x72/0xf0\n do_syscall_64+0x82/0x160\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nFix it by adding an argument to sched_move_task() that indicates whether the\nmoving is for a cgroup or autogroup migration. After the change,\nscx_move_task() is called only for cgroup migrations and renamed to\nscx_cgroup_move_task()."
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"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: sched_ext: Se corrige la detección incorrecta de la migración de autogrupos. scx_move_task() se llama desde sched_move_task() y le dice al programador BPF que se está confirmando la migración de cgroup. sched_move_task() se usa tanto en las migraciones de cgroup como de autogrupos y scx_move_task() intentó filtrar las migraciones de autogrupos probando el cgroup de destino y PF_EXITING, pero esto no es suficiente. De hecho, sin etiquetar explícitamente el hilo que está realizando la migración de cgroup, no hay una buena manera de diferenciar las invocaciones de scx_move_task() para la migración de ejecución al cgroup raíz y una migración de autogrupo. Esto provocó que scx_move_task() ignorara incorrectamente una migración desde un cgroup no raíz a un autogrupo del cgroup raíz, lo que activaba la siguiente advertencia: ADVERTENCIA: CPU: 7 PID: 1 en kernel/sched/ext.c:3725 scx_cgroup_can_attach+0x196/0x340 ... Seguimiento de llamadas: cgroup_migrate_execute+0x5b1/0x700 cgroup_attach_task+0x296/0x400 __cgroup_procs_write+0x128/0x140 cgroup_procs_write+0x17/0x30 kernfs_fop_write_iter+0x141/0x1f0 vfs_write+0x31d/0x4a0 __x64_sys_write+0x72/0xf0 do_syscall_64+0x82/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e Solucione el problema agregando un argumento a sched_move_task() que indique si el movimiento es para una migración de cgroup o de autogroup. Después del cambio, se llama a scx_move_task() solo para migraciones de cgroup y se le cambia el nombre a scx_cgroup_move_task()."
}
],
"lastModified": "2026-06-17T08:44:14.410",
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