ALSA: seq: Fix race at timer setup and close
Orabug:
23330523
commit
3567eb6af614dac436c4b16a8d426f9faed639b3 upstream.
ALSA sequencer code has an open race between the timer setup ioctl and
the close of the client. This was triggered by syzkaller fuzzer, and
a use-after-free was caught there as a result.
This patch papers over it by adding a proper queue->timer_mutex lock
around the timer-related calls in the relevant code path.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit
49c9eb3db86407868a664ade6da041fabeb457f8)
Signed-off-by: Dan Duval <dan.duval@oracle.com>