Vulnerability in Linux Kernel Affecting Random Number Generation

CVE-2025-21767

Summary

A bug in the Linux kernel involving the clock source verification process has been identified. This issue arises when the 'clocksource_verify_choose_cpus()' function, used for selecting CPUs based on random numbers, is called with preemption disabled. This can lead to attempts to acquire sleeping locks in an atomic context, causing system instability. The resolution involves utilizing 'migrate_disable()' to allow reliable use of 'smp_processor_id()' without introducing atomic context, thus mitigating the problem and ensuring the integrity of random number generation in the kernel.

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