ALSA: timer: Fix race among timer ioctls

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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>

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This commit is contained in:

Takashi Iwai 2016-01-13 17:48:01 +01:00

parent 91815d8aa7

commit af368027a4

1 changed files with 19 additions and 13 deletions

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32

sound/core/timer.c

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