static void nfc_llcp_recv_dm(struct nfc_llcp_local *local, struct sk_buff *skb)
{
	struct nfc_llcp_sock *llcp_sock;
	struct sock *sk;
	u8 dsap, ssap, reason;

	dsap = nfc_llcp_dsap(skb);
	ssap = nfc_llcp_ssap(skb);
	reason = skb->data[2];

	pr_debug("%d %d reason %d\n", ssap, dsap, reason);

	switch (reason) {
	case LLCP_DM_NOBOUND:
	case LLCP_DM_REJ:
		llcp_sock = nfc_llcp_connecting_sock_get(local, dsap);
		break;

	default:
		llcp_sock = nfc_llcp_sock_get(local, dsap, ssap);
		break;
	}

	if (llcp_sock == NULL) {
		pr_debug("Already closed\n");
		return;
	}

	sk = &llcp_sock->sk;

	sk->sk_err = ENXIO;
	sk->sk_state = LLCP_CLOSED;
	sk->sk_state_change(sk);

	nfc_llcp_sock_put(llcp_sock);
}

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