Bug 2492792 (CVE-2026-53192)

Summary: CVE-2026-53192 kernel: ALSA: timer: Fix UAF at snd_timer_user_params()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Advanced Linux Sound Architecture (ALSA) timer component. A race condition can occur during the release of a timer object, specifically when the SNDRV_TIMER_IOCTL_PARAMS ioctl is called concurrently. This can lead to a use-after-free vulnerability, potentially allowing a local attacker to achieve arbitrary code execution or cause a denial of service.
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Description OSIDB Bzimport 2026-06-25 10:05:59 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ALSA: timer: Fix UAF at snd_timer_user_params()

At releasing a timer object, e.g. when a userspace timer
(CONFIG_SND_UTIMER) gets closed and snd_timer_free() is called, it
tries to detach the timer instances and release the resources.
However, it's still possible that other in-flight tasks are holding
the timer instance where the to-be-deleted timer object is associated,
and this may lead to racy accesses.

Fortunately, most of ioctls dealing with the timer instance list
already have the protection with register_mutex, and this also avoids
such races.  But, SNDRV_TIMER_IOCTL_PARAMS isn't protected, hence the
concurrent ioctl may lead to use-after-free.

This patch just adds the guard with register_mutex to protect
snd_timer_user_params() for covering the code path as a quick
workaround.  It's no hot-path but rather a rarely issued ioctl, so the
performance penalty doesn't matter.
Comment 1 Keith Grant 2026-06-26 00:25:31 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062558-CVE-2026-53192-5b6e@gregkh/T