Like the previous fix (commit c0317c0e8709 "ALSA: timer: Fix use-after-free problem"), we have to unlink slave timer instances immediately at snd_timer_stop(), too. Otherwise it may leave a stale entry in the list if the slave instance is freed before actually running.
Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- v1->v2: return -EBUSY again if the instance isn't running
sound/core/timer.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/sound/core/timer.c b/sound/core/timer.c index 4f9bab931951..b3214baa8919 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -665,23 +665,22 @@ static int snd_timer_stop1(struct snd_timer_instance *timeri, bool stop) static int snd_timer_stop_slave(struct snd_timer_instance *timeri, bool stop) { unsigned long flags; + bool running;
spin_lock_irqsave(&slave_active_lock, flags); - if (!(timeri->flags & SNDRV_TIMER_IFLG_RUNNING)) { - spin_unlock_irqrestore(&slave_active_lock, flags); - return -EBUSY; - } + running = timeri->flags & SNDRV_TIMER_IFLG_RUNNING; timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING; if (timeri->timer) { spin_lock(&timeri->timer->lock); list_del_init(&timeri->ack_list); list_del_init(&timeri->active_list); - snd_timer_notify1(timeri, stop ? SNDRV_TIMER_EVENT_STOP : - SNDRV_TIMER_EVENT_PAUSE); + if (running) + snd_timer_notify1(timeri, stop ? SNDRV_TIMER_EVENT_STOP : + SNDRV_TIMER_EVENT_PAUSE); spin_unlock(&timeri->timer->lock); } spin_unlock_irqrestore(&slave_active_lock, flags); - return 0; + return running ? 0 : -EBUSY; }
/*