CVE-2025-21767

Siemens ProductCERT Advisory SSA-082556

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.

Metrics

Severity
none
no public PoC known
5.9 %
Low — this CVE sits in the lower 10% of all CVEs scored today.
0.2 %
Low — model estimates < 1% exploitation likelihood.
Published
2021-09-26 00:00 UTC

Affected operating systems

  • bsd

    freebsd / freebsd13.2

  • bsd

    freebsd / freebsd13.3

  • bsd

    freebsd / freebsd14.0

  • bsd

    freebsd / freebsd14.1

  • bsd

    netbsd / netbsd

  • linux

    almalinux / almalinux9.0

  • linux

    amazon / amazon_linux2023.0

  • linux

    amazon / amazon_linux

  • linux

    ubuntu / awsbionic

  • linux

    ubuntu / awsjammy

  • linux

    ubuntu / awsnoble

  • linux

    ubuntu / awsresolute

  • linux

    ubuntu / awsxenial

  • linux

    ubuntu / aws-6.8jammy

  • linux

    ubuntu / aws-hwexenial

  • linux

    ubuntu / azurejammy

  • linux

    ubuntu / azurenoble

  • linux

    ubuntu / azureresolute

  • linux

    ubuntu / azurexenial

  • linux

    ubuntu / azure-4.15bionic

  • linux

    suse / basesystem_module15

  • linux

    debian / debian_linux10.0

  • linux

    debian / debian_linux11.0

  • linux

    debian / debian_linux12.0

Affected products

Products and version ranges extracted from the vendor/CERT advisory. A range like „<4.14.6“ implies the update recommendation „upgrade to 4.14.6 or later“.

  • android

    :linux_kernel::0

  • android

    :linux_kernel:Kernel

  • arista

    cloudvision_agni2024.4.0 – 2025.2.2

  • arista

    cloudvision_portal2024.2.0 – 2026.1.0

  • arista

    velocloud_edge4.5.0 – 6.4.1

  • arista

    velocloud_gateway

  • arista

    velocloud_orchestrator

  • bitnami

    java-min1.9.0

  • bitnami

    varnish6.1.0

  • bitnami

    varnish7.4.0

  • Dell

    ECS3.8.1.0-3.8.1.7

  • Dell

    NetWorkervProxy 19.14

  • Dell

    PowerScale OneFSNode Firmware Package 14.1

  • Dell

    Secure Connect GatewayAppliance 5.32.00.18

  • Dell

    Secure Connect Gateway< 5.36.00.16

    fixed in 5.36.00.16

  • Dell

    Secure Connect GatewayAppliance <5.32.00.18

  • gnu

    glibc2.35 – 2.37

  • gnu

    glibc

  • gnupg

    libgcrypt1.11.0 – 1.11.3

  • gnupg

    libgcrypt1.12.0 – 1.12.2

  • gnupg

    libgcrypt1.8.8 – 1.10.4

  • hackage

    xz-clib5.6.3

  • hackage

    xz-clib5.6.4

  • hackage

    xz-clib5.8.0

References & sources

Linked CVEs

Show 291 more CVEs
IDCVE-2025-21767