CVE-2026-89979

CVE Details

Release Date:	2026-09-16
Impact:	Moderate	What is this?

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: Fix race between non-atomic ops and trigger-start We protect the races of the concurrent state transitions between atomic PCM ops, but the checks between the non-atomic ops (hw_params, hw_free and prepare) and the atomic ops aren't perfect; there is a check of the conflicting PCM state at the beginning of hw_params & co, but the atomic PCM ops can be still issued during the non-atomic PCM operations. An example such scenario is that a thread A re-issues the PREPARE or HW_PARAMS for the already prepared stream, while another thread B triggers the PCM start in the middle of the prepare operation. Although this usually doesn't lead to much serious issues, it can give some inconsistency as reported by syzkaller (such as ODEBUG warning). There are various atomic PCM ops, and basically the only problem is the PCM start as it operates from the PREPARED state. Other trigger commands (stop, etc) are for the running or the other special state, hence they are filtered as pre-condition. This patch is for preventing the PCM trigger-start during the non- atomic operations in order to address the problems above. Fortunately, the hw_params, hw_free and prepare operations call snd_pcm_buffer_access_lock(), and this can be used for checking the concurrent operations at the PCM trigger -- which sets the runtime->buffer_accessing to a negative (if possible), so the PCM trigger just needs to check the runtime->buffer_accessing value; if it's negative, it means the concurrent non-atomic PCM ops is running.

See more information about CVE-2026-89979 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	5.3
Vector String:	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
Version:	3.1
Attack Vector:	Local
Attack Complexity:	Low
Privileges Required:	Low
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	Low
Integrity Impact:	Low
Availability Impact:	Low

Errata information

Platform	Errata	Release Date
Oracle Linux version 9 (kernel-uek)	ELSA-2026-500374	2026-10-07