CVE-2025-21771 (GCVE-0-2025-21771)

Vulnerability from cvelistv5 – Published: 2025-02-27 02:18 – Updated: 2025-05-04 07:20
VLAI?
Title
sched_ext: Fix incorrect autogroup migration detection
Summary
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. 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: 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+0x76/0x7e 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().
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 8195136669661fdfe54e9a8923c33b31c92fc1da , < 75bf2f80c046d2ec5a07455891ea0a9fb6d8b5f6 (git)
Affected: 8195136669661fdfe54e9a8923c33b31c92fc1da , < d8b510d0ddc65d8a71e0f9a3acc9ed5f010fc514 (git)
Affected: 8195136669661fdfe54e9a8923c33b31c92fc1da , < d6f3e7d564b2309e1f17e709a70eca78d7ca2bb8 (git)
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    Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.12.16 , ≤ 6.12.* (semver)
Unaffected: 6.13.4 , ≤ 6.13.* (semver)
Unaffected: 6.14 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/autogroup.c",
            "kernel/sched/core.c",
            "kernel/sched/ext.c",
            "kernel/sched/ext.h",
            "kernel/sched/sched.h"
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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  \u003cTASK\u003e\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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        "dateUpdated": "2025-05-04T07:20:45.331Z",
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      "title": "sched_ext: Fix incorrect autogroup migration detection",
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    "cveId": "CVE-2025-21771",
    "datePublished": "2025-02-27T02:18:19.050Z",
    "dateReserved": "2024-12-29T08:45:45.762Z",
    "dateUpdated": "2025-05-04T07:20:45.331Z",
    "state": "PUBLISHED"
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    "nvd": "{\"cve\":{\"id\":\"CVE-2025-21771\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-02-27T03:15:17.767\",\"lastModified\":\"2025-10-28T20:30:43.293\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"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  \u003cTASK\u003e\\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().\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: sched_ext: Se corrige la detecci\u00f3n incorrecta de la migraci\u00f3n de autogrupos. scx_move_task() se llama desde sched_move_task() y le dice al programador BPF que se est\u00e1 confirmando la migraci\u00f3n de cgroup. sched_move_task() se usa tanto en las migraciones de cgroup como de autogrupos y scx_move_task() intent\u00f3 filtrar las migraciones de autogrupos probando el cgroup de destino y PF_EXITING, pero esto no es suficiente. De hecho, sin etiquetar expl\u00edcitamente el hilo que est\u00e1 realizando la migraci\u00f3n de cgroup, no hay una buena manera de diferenciar las invocaciones de scx_move_task() para la migraci\u00f3n de ejecuci\u00f3n al cgroup ra\u00edz y una migraci\u00f3n de autogrupo. Esto provoc\u00f3 que scx_move_task() ignorara incorrectamente una migraci\u00f3n desde un cgroup no ra\u00edz a un autogrupo del cgroup ra\u00edz, 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 migraci\u00f3n de cgroup o de autogroup. Despu\u00e9s del cambio, se llama a scx_move_task() solo para migraciones de cgroup y se le cambia el nombre a scx_cgroup_move_task().\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.12\",\"versionEndExcluding\":\"6.12.16\",\"matchCriteriaId\":\"537F3B42-2EC5-47FB-8166-5ACF0353AFEC\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.13.4\",\"matchCriteriaId\":\"2A2093ED-74A9-43F9-AC72-50030F374EA4\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"186716B6-2B66-4BD0-852E-D48E71C0C85F\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"0D3E781C-403A-498F-9DA9-ECEE50F41E75\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/75bf2f80c046d2ec5a07455891ea0a9fb6d8b5f6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/d6f3e7d564b2309e1f17e709a70eca78d7ca2bb8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/d8b510d0ddc65d8a71e0f9a3acc9ed5f010fc514\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
  }
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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