jffs2: free jffs2_sb_info through jffs2_kill_sb()

commit 92e2921f7eee63450a5f953f4b15dc6210219430 upstream.

When an invalid mount option is passed to jffs2, jffs2_parse_options()
will fail and jffs2_sb_info will be freed, but then jffs2_sb_info will
be used (use-after-free) and freeed (double-free) in jffs2_kill_sb().

Fix it by removing the buggy invocation of kfree() when getting invalid
mount options.

Fixes: 92abc475d8de ("jffs2: implement mount option parsing and compression overriding")
Cc: stable@kernel.org
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/jffs2/super.c

@@ -285,10 +285,8 @@ static int jffs2_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_fs_info = c;
 
 	ret = jffs2_parse_options(c, data);
-	if (ret) {
-		kfree(c);
+	if (ret)
 		return -EINVAL;
-	}
 
 	/* Initialize JFFS2 superblock locks, the further initialization will
 	 * be done later */