CVE-2026-80716ALSA: pcm: wake linked drain waiters on unlink

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/c172e4c53321ee6429955295ea133bc3597a3ca9
• https://git.kernel.org/stable/c/3035bb784cea3f338934f5042dd3f35225a51b2e
• https://git.kernel.org/stable/c/1c1b7e8e545ce65e40f65b55c432765e058ea98f
• https://git.kernel.org/stable/c/e8b784a3f4fba3ea9c4d05138ecfa784a069627f
• https://git.kernel.org/stable/c/e8315330e4ec09c0cac625515400e13d0ee22b81
• https://git.kernel.org/stable/c/2940cc3cf43c72126b74ee6376314c195382023a
• https://git.kernel.org/stable/c/db09bc4ab19ce548a078240d2374792523953500
• https://git.kernel.org/stable/c/f495b6c4c8594122918552c9be2b51eb71647cd9