Commit ee8413b0 authored Jan 13, 2016 by Takashi Iwai

ALSA: timer: Fix double unlink of active_list



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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent c4a359a0

sound/core/timer.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -694,7 +694,7 @@ 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))

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