CVE Catalog

CVE-2026-99104

Unknown
Published: Translated: NVD NIST

Summary

In the Linux kernel sched_ext scheduler, scx_bypass() claims bypass dispatch only for the scheduler whose depth goes from zero to one but does not propagate the claim to descendants. This leaks the claim when a sub-scheduler is enabled/disabled during PM suspend, leading to WARN_ON_ONCE or tasks left on bypass DSQs with no consumer.

Risk Assessment

A kernel warning may occur, and sub-scheduler tasks may remain unserviced on bypass DSQs, causing task stalls or delays. The issue affects systems using hierarchical sched_ext schedulers during suspend/resume.

Recommendation

Update the Linux kernel to a version with the fix that propagates the claim to descendants and releases it for the whole subtree. Avoid enabling/disabling sched_ext sub-schedulers during PM suspend until patched.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor scx_bypass() claims bypass dispatch when the scheduler's depth goes from zero to one and releases it when the depth returns to zero, but propagates only the depth to the descendants, not the claim. A descendant that starts bypassing with its ancestor never claims, and one whose own bypass ends under the ancestor's keeps its claim, as its depth does not return to zero. A sub-scheduler enable whose bypass ends under a PM suspend thus leaks its claim: the parent keeps hosting bypass dispatch and the sub-scheduler's next bypass trips the WARN_ON_ONCE() on the claim. A sub-scheduler disable that starts under a PM suspend has no claim, so once the resume lifts the root's bypass its tasks sit on the parent's bypass DSQs with nobody consuming them. Claim for every descendant whose depth goes from zero to one in the propagation and release every scheduler in the subtree whose depth returned to zero once the tasks have moved out of the bypass DSQs. A parent that is bypassing itself when a descendant claims consumes only its own bypass DSQs, empty until it leaves bypass and becomes the host.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS