CVE-2026-43482: sched_ext: Disable preemption between scx_claim_exit() and kicking helper work
In the Linux kernel, the following vulnerability has been resolved:
schedext: Disable preemption between scxclaimexit() and kicking helper work
scxclaimexit() atomically sets exitkind, which prevents scxerror() from triggering further error handling. After claiming exit, the caller must kick the helper kthread work which initiates bypass mode and teardown.
If the calling task gets preempted between claiming exit and kicking the helper work, and the BPF scheduler fails to schedule it back (since error handling is now disabled), the helper work is never queued, bypass mode never activates, tasks stop being dispatched, and the system wedges.
Disable preemption across scxclaimexit() and the subsequent work kicking in all callers - scxdisable() and scxvexit(). Add lockdepassertpreemptiondisabled() to scxclaimexit() to enforce the requirement.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Disable preemption across scx_claim_exit() and the subsequent work that kicks the helper kthread for bypass mode/teardown, so callers hold preemption-disabled state from scx_claim_exit() until the helper work is kicked (per lockdep_assert_preemption_disabled() enforcement).
Linux kernel sched_ext preemption behavior between scx_claim_exit() and kicking helper work (helper kthread) = disabled
Event History
Frequently Asked Questions
What is the severity of CVE-2026-43482?
CVE-2026-43482 is categorized as a medium severity vulnerability in the Linux kernel.
How does CVE-2026-43482 affect the Linux kernel?
CVE-2026-43482 affects the Linux kernel by disabling preemption between specific operations in the scheduling extension.
How do I fix CVE-2026-43482?
To fix CVE-2026-43482, update the Linux kernel to the latest version that includes the patch for this vulnerability.
What is the impact of CVE-2026-43482 on system performance?
The impact of CVE-2026-43482 on system performance may include potential scheduling delays due to the disabled preemption.
Is CVE-2026-43482 present in all Linux kernel versions?
CVE-2026-43482 is not present in all Linux kernel versions; it specifically affects versions prior to the application of the relevant patches.