exfat: fix memory leak in exfat_load_bitmap()

BugLink: https://bugs.launchpad.net/bugs/2086242

commit d2b537b3e533f28e0d97293fe9293161fe8cd137 upstream.

If the first directory entry in the root directory is not a bitmap
directory entry, 'bh' will not be released and reassigned, which
will cause a memory leak.

Fixes: 1e49a94 ("exfat: add bitmap operations")
Cc: stable@vger.kernel.org
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Aoyama Wataru <wataru.aoyama@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>

Author: YuezhangMo

fs/exfat/balloc.c

@@ -110,18 +110,18 @@ int exfat_load_bitmap(struct super_block *sb)
 				return -EIO;
 
 			type = exfat_get_entry_type(ep);
-			if (type == TYPE_UNUSED)
-				break;
-			if (type != TYPE_BITMAP)
-				continue;
-			if (ep->dentry.bitmap.flags == 0x0) {
+			if (type == TYPE_BITMAP &&
+			    ep->dentry.bitmap.flags == 0x0) {
 				int err;
 
 				err = exfat_allocate_bitmap(sb, ep);
 				brelse(bh);
 				return err;
 			}
 			brelse(bh);
+
+			if (type == TYPE_UNUSED)
+				return -EINVAL;
 		}
 
 		if (exfat_get_next_cluster(sb, &clu.dir))