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CVE PROGRAM SOURCE RECORDUnscored

CVE-2025-21767

clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context

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Status
Published
Published
Updated
Assigning organization
Linux

Description

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 products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • d9b40ebd448e437ffbc65f013836f98252279a82 to < d9c217fadfcff7a8df58567517d1e4253f3fd243affected
  • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 to < 60f54f0d4ea530950549a8263e6fdd70a40490a4affected
  • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 to < 852805b6cbdb69c298a8fc9fbe79994c95106e04affected
  • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 to < 8783ceeee797d9aa9cfe150690fb9d0bac8cc459affected
  • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 to < cc3d79e7c806cb57d71c28a4a35e7d7fb3265faaaffected
  • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 to < 0fb534187d2355f6c8f995321e76d1ccd1262ac1affected
  • 7560c02bdffb7c52d1457fa551b9e745d4b9e754 to < 6bb05a33337b2c842373857b63de5c9bf1ae2a09affected
  • 193e14e68e907b2a7a936a7726accbaa4df25a4daffected
  • 155d3c5d24ee13cafa6236b49fc02b240a511d59affected
  • 5.10.50 to < 5.10.235affected
  • 5.12.17 to < 5.13affected
  • 5.13.2 to < 5.14affected

Linux Linux

Default version status: affected

  • 5.14affected
  • 0 to < 5.14unaffected
  • 5.10.235 to ≤ 5.10.*unaffected
  • 5.15.179 to ≤ 5.15.*unaffected
  • 6.1.129 to ≤ 6.1.*unaffected
  • 6.6.79 to ≤ 6.6.*unaffected
  • 6.12.16 to ≤ 6.12.*unaffected
  • 6.13.4 to ≤ 6.13.*unaffected
  • 6.14 to ≤ *unaffected

References