CVE-2026-74731 - sched_ext: Skip sub-disable teardown for never-linked sub-schedulers
CVE ID :CVE-2026-74731
Published : Aug. 22, 2026, 3:33 p.m. | 29 minutes ago
Description :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.
Severity: 0.0 | NA
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Published : Aug. 22, 2026, 3:33 p.m. | 29 minutes ago
Description :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.
Severity: 0.0 | NA
Visit the link for more details, such as CVSS details, affected products, timeline, and more...