sched_ext: Skip sub-disable teardown for never-linked sub-schedulers

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74731
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:48 UTC
Updated2026-08-22 16:16:48 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 337ec00b1d9c676f637651c2cefddb8612b867ee 6428093a4a986c38c9089b5eb32b56d914ef437a git Not specified
CNA Linux Linux affected 337ec00b1d9c676f637651c2cefddb8612b867ee 8c13364db9c9a43ed286f3a8d0fb9477b1adc43c git Not specified
CNA Linux Linux affected 7.1 Not specified
CNA Linux Linux unaffected 7.1 semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/6428093a4a986c38c9089b5eb32b56d914ef437a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8c13364db9c9a43ed286f3a8d0fb9477b1adc43c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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