fkie_cve-2025-21767
Vulnerability from fkie_nvd
Published
2025-02-27 03:15
Modified
2025-10-28 20:28
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0fb534187d2355f6c8f995321e76d1ccd1262ac1Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/60f54f0d4ea530950549a8263e6fdd70a40490a4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6bb05a33337b2c842373857b63de5c9bf1ae2a09Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/852805b6cbdb69c298a8fc9fbe79994c95106e04Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8783ceeee797d9aa9cfe150690fb9d0bac8cc459Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cc3d79e7c806cb57d71c28a4a35e7d7fb3265faaPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d9c217fadfcff7a8df58567517d1e4253f3fd243Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 6.14


To clipboard 

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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nclocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context\n\nThe following bug report happened with a PREEMPT_RT kernel:\n\n  BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48\n  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog\n  preempt_count: 1, expected: 0\n  RCU nest depth: 0, expected: 0\n  get_random_u32+0x4f/0x110\n  clocksource_verify_choose_cpus+0xab/0x1a0\n  clocksource_verify_percpu.part.0+0x6b/0x330\n  clocksource_watchdog_kthread+0x193/0x1a0\n\nIt is due to the fact that clocksource_verify_choose_cpus() is invoked with\npreemption disabled.  This function invokes get_random_u32() to obtain\nrandom numbers for choosing CPUs.  The batched_entropy_32 local lock and/or\nthe base_crng.lock spinlock in driver/char/random.c will be acquired during\nthe call. In PREEMPT_RT kernel, they are both sleeping locks and so cannot\nbe acquired in atomic context.\n\nFix this problem by using migrate_disable() to allow smp_processor_id() to\nbe reliably used without introducing atomic context. preempt_disable() is\nthen called after clocksource_verify_choose_cpus() but before the\nclocksource measurement is being run to avoid introducing unexpected\nlatency."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: clocksource: Use migrants_disable() para evitar llamar a get_random_u32() en un contexto at\u00f3mico El siguiente informe de error ocurri\u00f3 con un kernel PREEMPT_RT: ERROR: funci\u00f3n inactiva llamada desde un contexto no v\u00e1lido en kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog preempt_count: 1, expected: 0 Profundidad de anidamiento de RCU: 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 Esto se debe al hecho de que clocksource_verify_choose_cpus() se invoca con la preempci\u00f3n deshabilitada. Esta funci\u00f3n invoca get_random_u32() para obtener n\u00fameros aleatorios para elegir las CPU. El bloqueo local batched_entropy_32 y/o el spinlock base_crng.lock en driver/char/random.c se adquirir\u00e1n durante la llamada. En el kernel PREEMPT_RT, ambos son bloqueos inactivos y, por lo tanto, no se pueden adquirir en un contexto at\u00f3mico. Solucione este problema utilizando migrants_disable() para permitir que smp_processor_id() se utilice de manera confiable sin introducir un contexto at\u00f3mico. Luego, se llama a preempt_disable() despu\u00e9s de clocksource_verify_choose_cpus() pero antes de que se ejecute la medici\u00f3n de la fuente de reloj para evitar introducir una latencia inesperada."
    }
  ],
  "id": "CVE-2025-21767",
  "lastModified": "2025-10-28T20:28:33.057",
  "metrics": {
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        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2025-02-27T03:15:17.383",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
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          "lang": "en",
          "value": "CWE-667"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
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}


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