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

ALSA: core: Fix potential UAF after asynchronous card release

Usually a sound driver releases the resources assigned to the card via snd card free(), and it synchronizes with the whole release procedure. However, when the card is released asynchronously via snd card free when closed() like USB-audio driver, the situation is slightly different; although the snd card disconnect() call at the disconnection guarantees that any newer accesses will be gated, the in-flight tasks might be still accessing to the underlying card->dev device even after the disconnection, which would cause a use-after-free in the end, as reported by fuzzers.

For addressing the bug above, this patch takes the refcount of card->dev at initialization of the card object, and releases at its destructor. This assures the availability of the card->dev in its whole lifecycle.