1 files changed, 18 insertions, 3 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 578ab6305c3f..0ce52d46e4f8 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -348,11 +348,20 @@ failure:
 static void tcp_v6_mtu_reduced(struct sock *sk)
 {
 	struct dst_entry *dst;
+	u32 mtu;
 
 	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
 		return;
 
-	dst = inet6_csk_update_pmtu(sk, tcp_sk(sk)->mtu_info);
+	mtu = READ_ONCE(tcp_sk(sk)->mtu_info);
+
+	/* Drop requests trying to increase our current mss.
+	 * Check done in __ip6_rt_update_pmtu() is too late.
+	 */
+	if (tcp_mtu_to_mss(sk, mtu) >= tcp_sk(sk)->mss_cache)
+		return;
+
+	dst = inet6_csk_update_pmtu(sk, mtu);
 	if (!dst)
 		return;
 
@@ -433,6 +442,8 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	}
 
 	if (type == ICMPV6_PKT_TOOBIG) {
+		u32 mtu = ntohl(info);
+
 		/* We are not interested in TCP_LISTEN and open_requests
 		 * (SYN-ACKs send out by Linux are always <576bytes so
 		 * they should go through unfragmented).
@@ -443,7 +454,11 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 		if (!ip6_sk_accept_pmtu(sk))
 			goto out;
 
-		tp->mtu_info = ntohl(info);
+		if (mtu < IPV6_MIN_MTU)
+			goto out;
+
+		WRITE_ONCE(tp->mtu_info, mtu);
+
 		if (!sock_owned_by_user(sk))
 			tcp_v6_mtu_reduced(sk);
 		else if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
@@ -540,7 +555,7 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
 		opt = ireq->ipv6_opt;
 		if (!opt)
 			opt = rcu_dereference(np->opt);
-		err = ip6_xmit(sk, skb, fl6, sk->sk_mark, opt,
+		err = ip6_xmit(sk, skb, fl6, skb->mark ? : sk->sk_mark, opt,
 			       tclass, sk->sk_priority);
 		rcu_read_unlock();
 		err = net_xmit_eval(err);