CVE-2026-68201

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

ALSA: timer: drain a slaves callback before its master detaches it

snd_timer_close_locked() drains the closing instances own in-flight callback (IFLG_CALLBACK) before freeing it, but not its slaves. When a master instance is closed, remove_slave_links() clears each slaves ->timer; the slaves own close then reads timer == NULL and takes the branch that skips the drain entirely (snd_timer_stop_slave() also no-ops on a NULL timer). So a slave whose callback is still running when the master is closed is freed underneath the live callback, leading to use-after-free.

Drain the slaves too before remove_slave_links() severs them. snd_timer_stop() has already taken this instance off the active list, so no new slave callback can be queued. Take the slaves off the ack list so a pending one cant fire either, then wait for any that is already in flight.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/2b298997786876b225cff2446e11a0fa6f602f6d
• https://git.kernel.org/stable/c/426c0ff1c433d6030610ad4f9375746dfe931caa
• https://git.kernel.org/stable/c/bdefe1346a8e6b8dc8593406dc2617e985fcbcab
• https://git.kernel.org/stable/c/cd461bcfcdf8d6b6b5365941c1d3859f8bc77aa0