1 files changed, 9 insertions, 1 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 9e041fa5c545..cd426313a298 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -943,9 +943,11 @@ static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
         if (skb) {
                 __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);
 
+                rcu_read_lock();
                 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
                                             ireq->ir_rmt_addr,
-                                            ireq_opt_deref(ireq));
+                                            rcu_dereference(ireq->ireq_opt));
+                rcu_read_unlock();
                 err = net_xmit_eval(err);
         }
 
@@ -2517,6 +2519,12 @@ static int __net_init tcp_sk_init(struct net *net)
                 if (res)
                         goto fail;
                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
+
+                /* Please enforce IP_DF and IPID==0 for RST and
+                 * ACK sent in SYN-RECV and TIME-WAIT state.
+                 */
+                inet_sk(sk)->pmtudisc = IP_PMTUDISC_DO;
+
                 *per_cpu_ptr(net->ipv4.tcp_sk, cpu) = sk;
         }