ubifs: Don't parse authentication mount options in remount process

There is no need to dump authentication options while remounting,
because authentication initialization can only be doing once in
the first mount process. Dumping authentication mount options in
remount process may cause memory leak if UBIFS has already been
mounted with old authentication mount options.
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Cc: <stable@vger.kernel.org>  # 4.20+
Fixes: d8a22773 ("ubifs: Enable authentication support")
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/super.c

@@ -1110,14 +1110,20 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
 			break;
 		}
 		case Opt_auth_key:
-			c->auth_key_name = kstrdup(args[0].from, GFP_KERNEL);
+			if (!is_remount) {
+				c->auth_key_name = kstrdup(args[0].from,
+								GFP_KERNEL);
 				if (!c->auth_key_name)
 					return -ENOMEM;
+			}
 			break;
 		case Opt_auth_hash_name:
-			c->auth_hash_name = kstrdup(args[0].from, GFP_KERNEL);
+			if (!is_remount) {
+				c->auth_hash_name = kstrdup(args[0].from,
+								GFP_KERNEL);
 				if (!c->auth_hash_name)
 					return -ENOMEM;
+			}
 			break;
 		case Opt_ignore:
 			break;