CVE-2025-21767: In the Linux kernel, the following vulnerability has been resolved: clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context The…

PriorityP420medium5.5CVSS 3.1

AVLACLPRLUINSUCNINAH

EPSS

0.16%

5.9th percentile

In the Linux kernel, the following vulnerability has been resolved: clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context The following bug report happened with a PREEMPT_RT kernel: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 get_random_u32+0x4f/0x110 clocksource_verify_choose_cpus+0xab/0x1a0 clocksource_verify_percpu.part.0+0x6b/0x330 clocksource_watchdog_kthread+0x193/0x1a0 It is due to the fact that clocksource_verify_choose_cpus() is invoked with preemption disabled. This function invokes get_random_u32() to obtain random numbers for choosing CPUs. The batched_entropy_32 local lock and/or the base_crng.lock spinlock in driver/char/random.c will be acquired during the call. In PREEMPT_RT kernel, they are both sleeping locks and so cannot be acquired in atomic context. Fix this problem by using migrate_disable() to allow smp_processor_id() to be reliably used without introducing atomic context. preempt_disable() is then called after clocksource_verify_choose_cpus() but before the clocksource measurement is being run to avoid introducing unexpected latency.

Affected

29 ranges· showing 25

Vendor	Product	Version range	Fixed in
debian	linux	< linux 6.1.129-1 (bookworm)	linux 6.1.129-1 (bookworm)
debian	linux-6.1	< linux 6.1.129-1 (bookworm)	linux 6.1.129-1 (bookworm)
linux	linux	—	—
linux	linux	—	—
linux	linux	—	—
linux	linux	>= 5.10.50 < 5.10.235	5.10.235
linux	linux	>= 5.12.17 < 5.13	5.13
linux	linux	>= 5.13.2 < 5.14	5.14
linux	linux	>= 7560c02bdffb7c52d1457fa551b9e745d4b9e754 < 60f54f0d4ea530950549a8263e6fdd70a40490a4	60f54f0d4ea530950549a8263e6fdd70a40490a4
linux	linux	>= 7560c02bdffb7c52d1457fa551b9e745d4b9e754 < 852805b6cbdb69c298a8fc9fbe79994c95106e04	852805b6cbdb69c298a8fc9fbe79994c95106e04
linux	linux	>= 7560c02bdffb7c52d1457fa551b9e745d4b9e754 < 8783ceeee797d9aa9cfe150690fb9d0bac8cc459	8783ceeee797d9aa9cfe150690fb9d0bac8cc459
linux	linux	>= 7560c02bdffb7c52d1457fa551b9e745d4b9e754 < cc3d79e7c806cb57d71c28a4a35e7d7fb3265faa	cc3d79e7c806cb57d71c28a4a35e7d7fb3265faa
linux	linux	>= 7560c02bdffb7c52d1457fa551b9e745d4b9e754 < 0fb534187d2355f6c8f995321e76d1ccd1262ac1	0fb534187d2355f6c8f995321e76d1ccd1262ac1
linux	linux	>= 7560c02bdffb7c52d1457fa551b9e745d4b9e754 < 6bb05a33337b2c842373857b63de5c9bf1ae2a09	6bb05a33337b2c842373857b63de5c9bf1ae2a09
linux	linux	>= d9b40ebd448e437ffbc65f013836f98252279a82 < d9c217fadfcff7a8df58567517d1e4253f3fd243	d9c217fadfcff7a8df58567517d1e4253f3fd243
linux	linux_kernel	—	—
linux	linux_kernel	>= 0 < 5.10.237-1	5.10.237-1
linux	linux_kernel	>= 0 < 6.1.129-1	6.1.129-1
linux	linux_kernel	>= 0 < 6.12.16-1	6.12.16-1
linux	linux_kernel	>= 0 < 6.12.16-1	6.12.16-1
linux	linux_kernel	>= 0 < 5.15.0-140.150	5.15.0-140.150
linux	linux_kernel	>= 0 < 6.8.0-78.78	6.8.0-78.78
linux	linux_kernel	>= 5.10.50 < 5.10.235	5.10.235
linux	linux_kernel	>= 5.12.17 < 5.13	5.13
linux	linux_kernel	>= 5.13.2 < 5.15.179	5.15.179

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

osv8.8HIGH

vendor_ubuntu8.8HIGH

vendor_debian5.5MEDIUM

vendor_redhat5.5MEDIUM

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