High [CVE-2026-53193] Forcibly close timer instances at closing
This high-severity Red Hat Linux advisory covers CVE-2026-53193 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Forcibly close timer instances at closing When snd_timer object is freed via snd_timer_free() and still pending snd_timer_instance objects are assigned to the timer object, it tries to unlink all instances and just set NULL to each ti->timer, then releases the resources immediately.
The problem is, however, when there are slave timer instances that are associated with a master instance linked to this timer: namely, those slave instances still point to the freed timer object although the master instance is unlinked, which may lead to user-after-free.
The bug can be easily triggered particularly when a new userspace-driven timers (CONFIG_SND_UTIMER) is involved, since it can create and delete the timer object via a simple file open/close, while the other applications may keep accessing to that timer.
This patch is an attempt to paper over the problem above: now instead of just unlinking, call snd_timer_close[_locked]() forcibly for each pending timer instance, so that all assigned slave timer instances are properly detached, too.
Since snd_timer_close() might be called later by the driver that created that instance, the check of SNDRV_TIMER_IFLG_DEAD is added at the beginning, too. A flaw was found in the Linux kernel's Advanced Linux Sound Architecture (ALSA) timer component.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
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