Invalid Task State Transitions in Linux Kernel Scheduler

CVE-2025-39780

What is CVE-2025-39780?

In the Linux kernel, a vulnerability exists within the scheduler that can cause invalid task state transitions when using the sched_ext scheduler. This issue arises during class switch operations, particularly affecting tasks that are already dead, leading to warnings and potential system instability. The kernel fails to appropriately skip these dead tasks during scheduling transitions, resulting in alerts like 'Invalid task state transition 0 -> 3'. A fix has been implemented to ensure dead tasks are excluded from class switching, thereby preventing these erroneous state transitions and enhancing system reliability.

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