FKIE_CVE-2026-74731

Vulnerability from fkie_nvd - Published: 2026-08-22 16:16 - Updated: 2026-08-22 16:16
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Skip sub-disable teardown for never-linked sub-schedulers A sub-scheduler enable can fail before scx_link_sched() links the sched into the hierarchy, e.g. when the parent is already being disabled, and cleanup still runs the full scx_sub_disable(). That is racy against root disable: drain_descendants() is the only ordering between a sub's disable-time task walk and root disable's all-task teardown, and an unlinked sub is invisible to it. Root's teardown can thus run between the never-linked sub's drain and its walk, exiting every task to no scheduler. The walk then trips the membership WARN and re-homes the exited tasks onto the dying hierarchy, a use-after-free. Skip the cgroup ownership reset and the task walk if @sch was never linked, indicated by the empty ->sibling as unlinking only happens later in the same function. The membership WARN remains valid: a linked sub is always waited on by an ancestor's drain.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6428093a4a986c38c9089b5eb32b56d914ef437a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8c13364db9c9a43ed286f3a8d0fb9477b1adc43c
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/ext/ext.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "6428093a4a986c38c9089b5eb32b56d914ef437a",
              "status": "affected",
              "version": "337ec00b1d9c676f637651c2cefddb8612b867ee",
              "versionType": "git"
            },
            {
              "lessThan": "8c13364db9c9a43ed286f3a8d0fb9477b1adc43c",
              "status": "affected",
              "version": "337ec00b1d9c676f637651c2cefddb8612b867ee",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/ext/ext.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Skip sub-disable teardown for never-linked sub-schedulers\n\nA sub-scheduler enable can fail before scx_link_sched() links the sched into\nthe hierarchy, e.g. when the parent is already being disabled, and cleanup\nstill runs the full scx_sub_disable().\n\nThat is racy against root disable: drain_descendants() is the only ordering\nbetween a sub\u0027s disable-time task walk and root disable\u0027s all-task teardown,\nand an unlinked sub is invisible to it. Root\u0027s teardown can thus run between\nthe never-linked sub\u0027s drain and its walk, exiting every task to no\nscheduler.\n\nThe walk then trips the membership WARN and re-homes the exited tasks onto\nthe dying hierarchy, a use-after-free.\n\nSkip the cgroup ownership reset and the task walk if @sch was never linked,\nindicated by the empty -\u003esibling as unlinking only happens later in the same\nfunction. The membership WARN remains valid: a linked sub is always waited\non by an ancestor\u0027s drain."
    }
  ],
  "id": "CVE-2026-74731",
  "lastModified": "2026-08-22T16:16:48.257",
  "metrics": {},
  "published": "2026-08-22T16:16:48.257",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6428093a4a986c38c9089b5eb32b56d914ef437a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8c13364db9c9a43ed286f3a8d0fb9477b1adc43c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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