clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context
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.
CVE-2025-21767
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2025-21767
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "d9b40ebd448e437ffbc65f013836f98252279a82",
"lessThan": "d9c217fadfcff7a8df58567517d1e4253f3fd243",
"versionType": "git"
},
{
"status": "affected",
"version": "7560c02bdffb7c52d1457fa551b9e745d4b9e754",
"lessThan": "60f54f0d4ea530950549a8263e6fdd70a40490a4",
"versionType": "git"
},
{
"status": "affected",
"version": "7560c02bdffb7c52d1457fa551b9e745d4b9e754",
"lessThan": "852805b6cbdb69c298a8fc9fbe79994c95106e04",
"versionType": "git"
},
{
"status": "affected",
"version": "7560c02bdffb7c52d1457fa551b9e745d4b9e754",
"lessThan": "8783ceeee797d9aa9cfe150690fb9d0bac8cc459",
"versionType": "git"
},
{
"status": "affected",
"version": "7560c02bdffb7c52d1457fa551b9e745d4b9e754",
"lessThan": "cc3d79e7c806cb57d71c28a4a35e7d7fb3265faa",
"versionType": "git"
},
{
"status": "affected",
"version": "7560c02bdffb7c52d1457fa551b9e745d4b9e754",
"lessThan": "0fb534187d2355f6c8f995321e76d1ccd1262ac1",
"versionType": "git"
},
{
"status": "affected",
"version": "7560c02bdffb7c52d1457fa551b9e745d4b9e754",
"lessThan": "6bb05a33337b2c842373857b63de5c9bf1ae2a09",
"versionType": "git"
},
{
"status": "affected",
"version": "193e14e68e907b2a7a936a7726accbaa4df25a4d",
"versionType": "git"
},
{
"status": "affected",
"version": "155d3c5d24ee13cafa6236b49fc02b240a511d59",
"versionType": "git"
},
{
"status": "affected",
"version": "5.10.50",
"lessThan": "5.10.235",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.12.17",
"lessThan": "5.13",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.13.2",
"lessThan": "5.14",
"versionType": "semver"
}
],
"programFiles": [
"kernel/time/clocksource.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.235",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.179",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.129",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.79",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.16",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.13.4",
"versionType": "semver",
"lessThanOrEqual": "6.13.*"
},
{
"status": "unaffected",
"version": "6.14",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/time/clocksource.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2025-21767
Source reference:
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- Event
- #26940 · Revision 1
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