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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{
  "containers": {
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/autogroup.c",
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            "kernel/sched/sched.h"
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            "kernel/sched/sched.h"
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              "versionType": "semver"
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              "operator": "OR"
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      "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()."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-05-04T07:20:45.331Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/75bf2f80c046d2ec5a07455891ea0a9fb6d8b5f6"
        },
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          "url": "https://git.kernel.org/stable/c/d8b510d0ddc65d8a71e0f9a3acc9ed5f010fc514"
        },
        {
          "url": "https://git.kernel.org/stable/c/d6f3e7d564b2309e1f17e709a70eca78d7ca2bb8"
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      ],
      "title": "sched_ext: Fix incorrect autogroup migration detection",
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    "assignerShortName": "Linux",
    "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"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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