ALSA: timer: Fix leak in events via snd_timer_user_tinterrupt

commit e4ec8cc8 upstream.

The stack object “r1” has a total size of 32 bytes. Its field
“event” and “val” both contain 4 bytes padding. These 8 bytes
padding bytes are sent to user without being initialized.
Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

sound/core/timer.c

@@ -1248,6 +1248,7 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri,
 	}
 	if ((tu->filter & (1 << SNDRV_TIMER_EVENT_RESOLUTION)) &&
 	    tu->last_resolution != resolution) {
+		memset(&r1, 0, sizeof(r1));
 		r1.event = SNDRV_TIMER_EVENT_RESOLUTION;
 		r1.tstamp = tstamp;
 		r1.val = resolution;