CVE-2026-68200

Status: UPDATED  |  Advisory ID: CVE-2026-68200

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

ALSA: timer: don't re-enter an instance callback that is still running

The userspace-driven timer (utimer) TRIGGER ioctl calls

snd_timer_interrupt() directly with no serialization, so two threads

triggering the same utimer can run snd_timer_interrupt() on one

snd_timer concurrently.

snd_timer_process_callbacks() drops timer->lock around each instance

callback and marks the in-flight callback with the single

SNDRV_TIMER_IFLG_CALLBACK bit; snd_timer_close_locked() waits on that

bit to drain an in-flight callback before freeing the instance. The bit

cannot represent two concurrent callbacks: when a second interrupt

re-queues an instance whose callback is still running, both run at once,

the first to finish clears the bit, and the close-path drain then frees

the instance (and its callback_data) while the other callback is still

live - a use-after-free reachable by any user able to open

/dev/snd/timer, both via a user timer instance and via a sequencer queue

timer bound to the utimer.

snd_timer_interrupt() sets IFLG_CALLBACK before dropping timer->lock, so

a concurrent interrupt already observes it under the lock. Skip

re-queuing an instance (and its slaves) to the ack/sack list while its

callback is in flight; the accumulated pticks are delivered on the next

tick, so no event is lost. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References