[PATCH] ALSA: timer: Fix master timer notification

[PATCH] ALSA: timer: Fix master timer notification

[Takashi Iwai]

snd_timer_notify1() calls the notification to each slave for a master
event, but it passes a wrong event number.  It should be +10 offset,
corresponding to SNDRV_TIMER_EVENT_MXXX, but it's incorrectly with
+100 offset.  Casually this was spotted by UBSAN check via syzkaller.

Reported-by: syzbot+d102fa5b35335a7e544e@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/000000000000e5560e05c3bd1d63@google.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/core/timer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/core/timer.c b/sound/core/timer.c
index 6898b1ac0d7f..92b7008fcdb8 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -520,9 +520,10 @@ static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
 		return;
 	if (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)
 		return;
+	event += 10; /* convert to SNDRV_TIMER_EVENT_MXXX */
 	list_for_each_entry(ts, &ti->slave_active_head, active_list)
 		if (ts->ccallback)
-			ts->ccallback(ts, event + 100, &tstamp, resolution);
+			ts->ccallback(ts, event, &tstamp, resolution);
 }
 
 /* start/continue a master timer */
-- 
2.26.2

Re: [PATCH] ALSA: timer: Fix master timer notification

[Jaroslav Kysela]

On 02. 06. 21 13:38, Takashi Iwai wrote:
> snd_timer_notify1() calls the notification to each slave for a master
> event, but it passes a wrong event number.  It should be +10 offset,
> corresponding to SNDRV_TIMER_EVENT_MXXX, but it's incorrectly with
> +100 offset.  Casually this was spotted by UBSAN check via syzkaller.
> 
> Reported-by: syzbot+d102fa5b35335a7e544e@syzkaller.appspotmail.com
> Cc: <stable@vger.kernel.org>
> Link: https://lore.kernel.org/r/000000000000e5560e05c3bd1d63@google.com
> Signed-off-by: Takashi Iwai <tiwai@suse.de>

Reviewed-by: Jaroslav Kysela <perex@perex.cz>

> ---
>  sound/core/timer.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/core/timer.c b/sound/core/timer.c
> index 6898b1ac0d7f..92b7008fcdb8 100644
> --- a/sound/core/timer.c
> +++ b/sound/core/timer.c
> @@ -520,9 +520,10 @@ static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
>  		return;
>  	if (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)
>  		return;
> +	event += 10; /* convert to SNDRV_TIMER_EVENT_MXXX */
>  	list_for_each_entry(ts, &ti->slave_active_head, active_list)
>  		if (ts->ccallback)
> -			ts->ccallback(ts, event + 100, &tstamp, resolution);
> +			ts->ccallback(ts, event, &tstamp, resolution);
>  }
>  
>  /* start/continue a master timer */
> 


-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.