Linux vulnerability

What happened

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.

Affected versions

Linux: b1c73fc8e697eb73e23603e465e9af2711ed4183 through before f57467114f40c5aacebbea96fb4ff9e5cd2b7f18 (git); b1c73fc8e697eb73e23603e465e9af2711ed4183 through before c99be0d5af02adebe9cb6f9869d20397fa9935a3 (git); b1c73fc8e697eb73e23603e465e9af2711ed4183 through before f3ce8be893726899e3053cf8059ecc95d8410359 (git); b1c73fc8e697eb73e23603e465e9af2711ed4183 through before 0e6245b2424d126ac90018142d09f0707e12998b (git); b1c73fc8e697eb73e23603e465e9af2711ed4183 through before bad15420050db1803767e58756114800cce91ea4 (git); b1c73fc8e697eb73e23603e465e9af2711ed4183 through before 5727ccf9d19ca414cb76d9b647883822e2789c2e (git); b1c73fc8e697eb73e23603e465e9af2711ed4183 through before 826af7fa62e347464b1b4e0ba2fe19a92438084f (git); 2.6.37 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.