static int netlink_create(struct net *net, struct socket *sock, int protocol,
			  int kern)
{
	struct module *module = NULL;
	struct mutex *cb_mutex;
	struct netlink_sock *nlk;
	int (*bind)(struct net *net, int group);
	void (*unbind)(struct net *net, int group);
	int err = 0;

	sock->state = SS_UNCONNECTED;

	if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
		return -ESOCKTNOSUPPORT;

	if (protocol < 0 || protocol >= MAX_LINKS)
		return -EPROTONOSUPPORT;

	netlink_lock_table();
#ifdef CONFIG_MODULES
	if (!nl_table[protocol].registered) {
		netlink_unlock_table();
		request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
		netlink_lock_table();
	}
#endif
	if (nl_table[protocol].registered &&
	    try_module_get(nl_table[protocol].module))
		module = nl_table[protocol].module;
	else
		err = -EPROTONOSUPPORT;
	cb_mutex = nl_table[protocol].cb_mutex;
	bind = nl_table[protocol].bind;
	unbind = nl_table[protocol].unbind;
	netlink_unlock_table();

	if (err < 0)
		goto out;

	err = __netlink_create(net, sock, cb_mutex, protocol, kern);
	if (err < 0)
		goto out_module;

	local_bh_disable();
	sock_prot_inuse_add(net, &netlink_proto, 1);
	local_bh_enable();

	nlk = nlk_sk(sock->sk);
	nlk->module = module;
	nlk->netlink_bind = bind;
	nlk->netlink_unbind = unbind;
out:
	return err;

out_module:
	module_put(module);
	goto out;
}

The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations.