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ALSA: timer: Fix double unlink of active_list

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commit ee8413b01045c74340aa13ad5bdf905de32be736 upstream.

ALSA timer instance object has a couple of linked lists and they are
unlinked unconditionally at snd_timer_stop().  Meanwhile
snd_timer_interrupt() unlinks it, but it calls list_del() which leaves
the element list itself unchanged.  This ends up with unlinking twice,
and it was caught by syzkaller fuzzer.

The fix is to use list_del_init() variant properly there, too.

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>
This commit is contained in:
Takashi Iwai 2016-01-13 21:35:06 +01:00 committed by Greg Kroah-Hartman
parent d87622a166
commit 3c0e535fee
1 changed files with 1 additions and 1 deletions
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2
sound/core/timer.c
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@ -704,7 +704,7 @@ void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
} else {
ti->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
if (--timer->running)
list_del(&ti->active_list);
list_del_init(&ti->active_list);
}
if ((timer->hw.flags & SNDRV_TIMER_HW_TASKLET) ||
(ti->flags & SNDRV_TIMER_IFLG_FAST))