tree ca51f654c1b2f2d660a211b2a21dacc57f36cb62
parent 91815d8aa7e2f45d30e51caa297061ad893628d9
author Takashi Iwai <tiwai@suse.de> 1452703681 +0100
committer Takashi Iwai <tiwai@suse.de> 1452776841 +0100

ALSA: timer: Fix race among timer ioctls

ALSA timer ioctls have an open race and this may lead to a
use-after-free of timer instance object.  A simplistic fix is to make
each ioctl exclusive.  We have already tread_sem for controlling the
tread, and extend this as a global mutex to be applied to each ioctl.

The downside is, of course, the worse concurrency.  But these ioctls
aren't to be parallel accessible, in anyway, so it should be fine to
serialize there.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>