Merge branch 'topic/ctl-add-remove-fixes' into for-linus

* topic/ctl-add-remove-fixes:
  sound: snd_ctl_remove_user_ctl: prevent removal of kernel controls
  sound: snd_ctl_remove_unlocked_id: simplify user control counting
  sound: snd_ctl_remove_unlocked_id: simplify error paths
  sound: snd_ctl_elem_add: fix value count check

sound/core/control.c

@@ -414,7 +414,7 @@ int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
 EXPORT_SYMBOL(snd_ctl_remove_id);
 
 /**
- * snd_ctl_remove_unlocked_id - remove the unlocked control of the given id and release it
+ * snd_ctl_remove_user_ctl - remove and release the unlocked user control
  * @file: active control handle
  * @id: the control id to remove
  *
@@ -423,7 +423,7 @@ EXPORT_SYMBOL(snd_ctl_remove_id);
  * 
  * Returns 0 if successful, or a negative error code on failure.
  */
-static int snd_ctl_remove_unlocked_id(struct snd_ctl_file * file,
+static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
 				   struct snd_ctl_elem_id *id)
 {
 	struct snd_card *card = file->card;
@@ -433,15 +433,23 @@ static int snd_ctl_remove_unlocked_id(struct snd_ctl_file * file,
 	down_write(&card->controls_rwsem);
 	kctl = snd_ctl_find_id(card, id);
 	if (kctl == NULL) {
-		up_write(&card->controls_rwsem);
-		return -ENOENT;
+		ret = -ENOENT;
+		goto error;
+	}
+	if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
+		ret = -EINVAL;
+		goto error;
 	}
 	for (idx = 0; idx < kctl->count; idx++)
 		if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {
-			up_write(&card->controls_rwsem);
-			return -EBUSY;
+			ret = -EBUSY;
+			goto error;
 		}
 	ret = snd_ctl_remove(card, kctl);
+	if (ret < 0)
+		goto error;
+	card->user_ctl_count--;
+error:
 	up_write(&card->controls_rwsem);
 	return ret;
 }
@@ -951,7 +959,7 @@ static int snd_ctl_elem_add(struct snd_ctl_file *file,
 	
 	if (card->user_ctl_count >= MAX_USER_CONTROLS)
 		return -ENOMEM;
-	if (info->count > 1024)
+	if (info->count < 1)
 		return -EINVAL;
 	access = info->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :
 		(info->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|
@@ -1052,18 +1060,10 @@ static int snd_ctl_elem_remove(struct snd_ctl_file *file,
 			       struct snd_ctl_elem_id __user *_id)
 {
 	struct snd_ctl_elem_id id;
-	int err;
 
 	if (copy_from_user(&id, _id, sizeof(id)))
 		return -EFAULT;
-	err = snd_ctl_remove_unlocked_id(file, &id);
-	if (! err) {
-		struct snd_card *card = file->card;
-		down_write(&card->controls_rwsem);
-		card->user_ctl_count--;
-		up_write(&card->controls_rwsem);
-	}
-	return err;
+	return snd_ctl_remove_user_ctl(file, &id);
 }
 
 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)