ALSA: timer: Fix master timer notification

commit 9c1fe96 upstream.

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: [email protected]
Reviewed-by: Jaroslav Kysela <[email protected]>
Cc: <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Lee Jones <[email protected]>
Change-Id: I553f43fc90b1bfc959805ad54fd8220c550ea671

sound/core/timer.c

@@ -432,9 +432,10 @@ 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 */