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Commit bf2a56e4 authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman
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ALSA: timer: Unconditionally unlink slave instances, too 

commit ffdd98277f0a1d15a67a74ae09bee713df4c0dbc upstream.

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>
Link: https://lore.kernel.org/r/20211105091517.21733-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2fd55584

sound/core/timer.c

+6 −7
Original line number Diff line number Diff line
@@ -634,23 +634,22 @@ 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);

		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;

}



/*