Data Corruption and Race Condition in Linux Kernel's KCOV on PREEMPT_RT Systems

CVE-2026-80916

What is CVE-2026-80916?

A vulnerability in the Linux kernel related to KCOV functionality has been identified, primarily affecting PREEMPT_RT configurations. The issue arises when softirq handlers, operating as preemptible tasks, preempt a task executing a remote KCOV session, leading to the overwriting of per-CPU storage areas. This race condition results in the loss of the original task's remote KCOV state, causing data corruption. The fix implements a transition to per-thread storage for temporary data, preventing nested softirq preemption from overwriting task contexts. Additionally, the patch addresses potential kernel crashes related to memory allocation failures, ensuring robust handling of KCOV state management in various operational contexts.

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