ovl: fix memory leak on unlink of indexed file

The memory leak was detected by kmemleak when running xfstests
overlay/051,053

Fixes: caf70cb2ba5d ("ovl: cleanup orphan index entries")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/util.c

@@ -683,7 +683,7 @@ static void ovl_cleanup_index(struct dentry *dentry)
 	struct dentry *upperdentry = ovl_dentry_upper(dentry);
 	struct dentry *index = NULL;
 	struct inode *inode;
-	struct qstr name;
+	struct qstr name = { };
 	int err;
 
 	err = ovl_get_index_name(lowerdentry, &name);
@@ -726,6 +726,7 @@ static void ovl_cleanup_index(struct dentry *dentry)
 		goto fail;
 
 out:
+	kfree(name.name);
 	dput(index);
 	return;