ALSA: bebob: potential info leak in hwdep_read()

The "count" variable needs to be capped on every path so that we don't
copy too much information to the user.

Fixes: 618eabeae7 ("ALSA: bebob: Add hwdep interface")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201007074928.GA2529578@mwanda
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/bebob/bebob_hwdep.c

@@ -36,12 +36,11 @@ hwdep_read(struct snd_hwdep *hwdep, char __user *buf,  long count,
 	}
 
 	memset(&event, 0, sizeof(event));
+	count = min_t(long, count, sizeof(event.lock_status));
 	if (bebob->dev_lock_changed) {
 		event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
 		event.lock_status.status = (bebob->dev_lock_count > 0);
 		bebob->dev_lock_changed = false;
-
-		count = min_t(long, count, sizeof(event.lock_status));
 	}
 
 	spin_unlock_irq(&bebob->lock);