Bug 2525473 (CVE-2026-80716)

Summary:	CVE-2026-80716 kernel: ALSA: pcm: wake linked drain waiters on unlink
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel. Specifically, in the Advanced Linux Sound Architecture (ALSA) Pulse-Code Modulation (PCM) subsystem, a use-after-free vulnerability exists. This occurs when a linked stream is unlinked, and a wait entry is not properly removed from the drained peer's sleep list. A local attacker could exploit this to cause a system crash (denial of service) or potentially execute arbitrary code by accessing a freed memory location.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-08-28 07:46:46 UTC

In the Linux kernel, the following vulnerability has been resolved:

ALSA: pcm: wake linked drain waiters on unlink

snd_pcm_drain() on a linked stream parks an on-stack wait entry on the
drained peer's runtime->sleep, and after schedule_timeout() removes it
only if that peer is still found in the caller's group.  If group
membership changes during the wait and the sleep ends by signal or
timeout (so autoremove_wake_function() does not run), finish_wait() is
skipped and snd_pcm_drain() returns with the entry still queued on that
stream's sleep list; a later wake_up() then walks a freed stack frame.
This is reachable by unlinking either the drained or the draining stream.

Unlike the close path (snd_pcm_drop() -> snd_pcm_post_stop()),
snd_pcm_unlink() never wakes the sleep queues.  Wake every group member
under the group lock before the membership change, so a linked drainer is
released and drops its entry while the streams are still grouped.

The window was opened when snd_pcm_link_rwsem stopped being held across
the wait and the removal became conditional on group membership (see
Fixes). The later switch to finish_wait() kept that conditional removal,
so the signal/timeout case remained.

Comment 1 gkamathe 2026-09-01 07:46:40 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082809-CVE-2026-80716-33fd@gregkh/T