fs/exofs: fix potential memory leak in mount option parsing

BugLink: https://bugs.launchpad.net/bugs/1810958

[ Upstream commit 515f1867 ]

There are some cases can cause memory leak when parsing
option 'osdname'.
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

fs/exofs/super.c

@@ -100,6 +100,7 @@ static int parse_options(char *options, struct exofs_mountopt *opts)
 		token = match_token(p, tokens, args);
 		switch (token) {
 		case Opt_name:
+			kfree(opts->dev_name);
 			opts->dev_name = match_strdup(&args[0]);
 			if (unlikely(!opts->dev_name)) {
 				EXOFS_ERR("Error allocating dev_name");
@@ -868,8 +869,10 @@ static struct dentry *exofs_mount(struct file_system_type *type,
 	int ret;
 
 	ret = parse_options(data, &opts);
-	if (ret)
+	if (ret) {
+		kfree(opts.dev_name);
 		return ERR_PTR(ret);
+	}
 
 	if (!opts.dev_name)
 		opts.dev_name = dev_name;