From: Takashi Iwai Date: Fri, 5 Nov 2021 09:15:17 +0000 (+0100) Subject: ALSA: timer: Unconditionally unlink slave instances, too X-Git-Tag: v4.4.293~144 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9082aa14e202f452618f4513876f0bf086525d8e;p=thirdparty%2Fkernel%2Fstable.git 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: Link: https://lore.kernel.org/r/20211105091517.21733-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- diff --git a/sound/core/timer.c b/sound/core/timer.c index 41f4b33b18b9a..90ad22e24a71e 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -566,23 +566,22 @@ 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; } /*