ALSA: timer: Fix race among timer ioctls

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commit af368027a4 upstream.

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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Takashi Iwai 2016-01-13 17:48:01 +01:00 • committed by Greg Kroah-Hartman

parent af9bab84ca

commit d87622a166

1 changed files with 19 additions and 13 deletions

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sound/core/timer.c

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