CVE Catalog

CVE-2026-99144

Unknown
Published: Translated: NVD NIST

Summary

In the Linux kernel's sched_ext module, a deferred reenqueue can read a freed user DSQ. The request stays on its CPU's deferred list until run_deferred() takes it, and the RCU callback freeing the DSQ assumes the grace period flushed it, but a run_deferred() starting after the grace period began can detach the request right before the callback looks and read the freed DSQ's id.

Risk Assessment

A kernel use-after-free can lead to memory corruption, system instability, or privilege escalation by a local user.

Recommendation

Update the Linux kernel to a version with the fix that cancels pending requests before the grace period. Avoid using sched_ext 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 use-after-free of a destroyed user DSQ by a deferred reenqueue A deferred reenqueue can read a freed user DSQ. The request stays on its CPU's deferred list until run_deferred() takes it, and the RCU callback that frees the DSQ assumes that the grace period has flushed it, so exit_dsq() checks the per-CPU node without the deferred list lock. A grace period waits for readers in flight, not for a pending run_deferred(). A run_deferred() which starts after the grace period began can detach the request right before the callback looks and then read the freed DSQ's id. Cancel the pending requests before the grace period instead. The irq work that frees the DSQ unlinks every CPU's request under the per-CPU deferred list lock, and schedule_dsq_reenq() ignores a new request under the same lock once the id is invalid. Only a run_deferred() that started before the grace period can hold a request, and it runs with IRQs disabled, so the grace period waits for it and nothing touches the DSQ after the callback.

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