[IPV6] TCPMD5: Check return value of tcp_alloc_md5sig_pool().

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/tcp_ipv6.c

@@ -581,7 +581,10 @@ static int tcp_v6_md5_do_add(struct sock *sk, struct in6_addr *peer,
 			}
 			sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
 		}
-		tcp_alloc_md5sig_pool();
+		if (tcp_alloc_md5sig_pool() == NULL) {
+			kfree(newkey);
+			return -ENOMEM;
+		}
 		if (tp->md5sig_info->alloced6 == tp->md5sig_info->entries6) {
 			keys = kmalloc((sizeof (tp->md5sig_info->keys6[0]) *
 				       (tp->md5sig_info->entries6 + 1)), GFP_ATOMIC);