void nfs_fattr_map_and_free_names(struct nfs_server *server, struct nfs_fattr *fattr)
{
	if (nfs_fattr_map_owner_name(server, fattr))
		nfs_fattr_free_owner_name(fattr);
	if (nfs_fattr_map_group_name(server, fattr))
		nfs_fattr_free_group_name(fattr);
}

The product dereferences a pointer that it expects to be valid but is NULL.