CVE-2025-23134: ALSA: timer: Don't take register_mutex with copy_from/to_user()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-04-16 · updated 2026-06-17
Weakness: CWE-667

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Don't take register_mutex with copy_from/to_user() The infamous mmap_lock taken in copy_from/to_user() can be often problematic when it's called inside another mutex, as they might lead to deadlocks. In the case of ALSA timer code, the bad pattern is with guard(mutex)(&register_mutex) that covers copy_from/to_user() -- which was mistakenly introduced at converting to guard(), and it had been carefully worked around in the past. This patch fixes those pieces simply by moving copy_from/to_user() out of the register mutex lock again.

Affected products

Linux kernel: from 6.9 before 6.12.23; from 6.13 before 6.13.11; from 6.14 before 6.14.2 — fixed in 6.12.23, 6.13.11, 6.14.2

How to fix

Upgrade to a fixed version: Linux kernel 6.12.23, 6.13.11, 6.14.2. Check the vendor advisory for mitigations.

References

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