In the Linux kernel, the following vulnerability has been resolved:
ALSA: bcd2000: Fix race between rawmidi and disconnect
Although we tried to fix the potential UAF issues at USB disconnect on
bcd2000 driver, there is still an overlooked case -- namely, when a
rawmidi trigger callback has been already running at USB disconnect
handling, the in-flight function (e.g. bcd2000_midi_send()) could
still access the URB, because the previous URB NULL-check & clearance
was considered only for the URB complete callbacks, but not about the
parallel rawmidi operations.
For addressing the race, this patch introduced a new spinlock that
covers each rawmidi operation as well as the rawmidi handling in the
complete callback. The URB is cleared with the lock, so it guarantees
that the pending rawmidi task already finished or a NULL check is
effective.