ALSA: timer: Fix double unlink of active_list

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 <[email protected]> Tested-by: Dmitry Vyukov <[email protected]> Signed-off-by: Takashi Iwai <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> Signed-off-by: Willy Tarreau <[email protected]>
Shadowman94 · Mar 12, 2016 · 22c74cd · 22c74cd
1 parent b3f7ff5
commit 22c74cd
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/sound/core/timer.c b/sound/core/timer.c
@@ -724,7 +724,7 @@ 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))