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

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Summary

CVECVE-2025-21767
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-02-27 03:15:17 UTC
Updated2026-05-12 13:16:36 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-667

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d9b40ebd448e437ffbc65f013836f98252279a82 d9c217fadfcff7a8df58567517d1e4253f3fd243 git Not specified
CNA Linux Linux affected 7560c02bdffb7c52d1457fa551b9e745d4b9e754 60f54f0d4ea530950549a8263e6fdd70a40490a4 git Not specified
CNA Linux Linux affected 7560c02bdffb7c52d1457fa551b9e745d4b9e754 852805b6cbdb69c298a8fc9fbe79994c95106e04 git Not specified
CNA Linux Linux affected 7560c02bdffb7c52d1457fa551b9e745d4b9e754 8783ceeee797d9aa9cfe150690fb9d0bac8cc459 git Not specified
CNA Linux Linux affected 7560c02bdffb7c52d1457fa551b9e745d4b9e754 cc3d79e7c806cb57d71c28a4a35e7d7fb3265faa git Not specified
CNA Linux Linux affected 7560c02bdffb7c52d1457fa551b9e745d4b9e754 0fb534187d2355f6c8f995321e76d1ccd1262ac1 git Not specified
CNA Linux Linux affected 7560c02bdffb7c52d1457fa551b9e745d4b9e754 6bb05a33337b2c842373857b63de5c9bf1ae2a09 git Not specified
CNA Linux Linux affected 193e14e68e907b2a7a936a7726accbaa4df25a4d git Not specified
CNA Linux Linux affected 155d3c5d24ee13cafa6236b49fc02b240a511d59 git Not specified
CNA Linux Linux affected 5.14 Not specified
CNA Linux Linux unaffected 5.14 semver Not specified
CNA Linux Linux unaffected 5.10.235 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.179 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.129 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.79 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.16 6.12.* semver Not specified
CNA Linux Linux unaffected 6.13.4 6.13.* semver Not specified
CNA Linux Linux unaffected 6.14 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified

References

ReferenceSourceLinkTags
lists.debian.org/debian-lts-announce/2025/05/msg00030.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
git.kernel.org/stable/c/6bb05a33337b2c842373857b63de5c9bf1ae2a09 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/cc3d79e7c806cb57d71c28a4a35e7d7fb3265faa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-082556.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/852805b6cbdb69c298a8fc9fbe79994c95106e04 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/60f54f0d4ea530950549a8263e6fdd70a40490a4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/0fb534187d2355f6c8f995321e76d1ccd1262ac1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/d9c217fadfcff7a8df58567517d1e4253f3fd243 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/8783ceeee797d9aa9cfe150690fb9d0bac8cc459 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/03/msg00028.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
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