CVE-2026-23191

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

ALSA: aloop: Fix racy access at PCM trigger

The PCM trigger callback of aloop driver tries to check the PCM state

and stop the stream of the tied substream in the corresponding cable.

Since both check and stop operations are performed outside the cable

lock, this may result in UAF when a program attempts to trigger

frequently while opening/closing the tied stream, as spotted by

fuzzers.

For addressing the UAF, this patch changes two things:

- It covers the most of code in loopback_check_format() with

cable->lock spinlock, and add the proper NULL checks. This avoids

already some racy accesses.

- In addition, now we try to check the state of the capture PCM stream

that may be stopped in this function, which was the major pain point

leading to UAF.