4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Takashi Iwai <tiwai@xxxxxxx>
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@xxxxxxxxxx>
Tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/core/timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -704,7 +704,7 @@ void snd_timer_interrupt(struct snd_time
} 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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