1 files changed, 33 insertions, 31 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a12b455928e5..d107ee246a1d 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2315,6 +2315,35 @@ static inline bool tcp_packet_delayed(const struct tcp_sock *tp)
 
 /* Undo procedures. */
 
+/* We can clear retrans_stamp when there are no retransmissions in the
+ * window. It would seem that it is trivially available for us in
+ * tp->retrans_out, however, that kind of assumptions doesn't consider
+ * what will happen if errors occur when sending retransmission for the
+ * second time. ...It could the that such segment has only
+ * TCPCB_EVER_RETRANS set at the present time. It seems that checking
+ * the head skb is enough except for some reneging corner cases that
+ * are not worth the effort.
+ *
+ * Main reason for all this complexity is the fact that connection dying
+ * time now depends on the validity of the retrans_stamp, in particular,
+ * that successive retransmissions of a segment must not advance
+ * retrans_stamp under any conditions.
+ */
+static bool tcp_any_retrans_done(const struct sock *sk)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb;
+
+	if (tp->retrans_out)
+		return true;
+
+	skb = tcp_write_queue_head(sk);
+	if (unlikely(skb && TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS))
+		return true;
+
+	return false;
+}
+
 #if FASTRETRANS_DEBUG > 1
 static void DBGUNDO(struct sock *sk, const char *msg)
 {
@@ -2410,6 +2439,8 @@ static bool tcp_try_undo_recovery(struct sock *sk)
 		 * is ACKed. For Reno it is MUST to prevent false
 		 * fast retransmits (RFC2582). SACK TCP is safe. */
 		tcp_moderate_cwnd(tp);
+		if (!tcp_any_retrans_done(sk))
+			tp->retrans_stamp = 0;
 		return true;
 	}
 	tcp_set_ca_state(sk, TCP_CA_Open);
@@ -2430,35 +2461,6 @@ static bool tcp_try_undo_dsack(struct sock *sk)
 	return false;
 }
 
-/* We can clear retrans_stamp when there are no retransmissions in the
- * window. It would seem that it is trivially available for us in
- * tp->retrans_out, however, that kind of assumptions doesn't consider
- * what will happen if errors occur when sending retransmission for the
- * second time. ...It could the that such segment has only
- * TCPCB_EVER_RETRANS set at the present time. It seems that checking
- * the head skb is enough except for some reneging corner cases that
- * are not worth the effort.
- *
- * Main reason for all this complexity is the fact that connection dying
- * time now depends on the validity of the retrans_stamp, in particular,
- * that successive retransmissions of a segment must not advance
- * retrans_stamp under any conditions.
- */
-static bool tcp_any_retrans_done(const struct sock *sk)
-{
-	const struct tcp_sock *tp = tcp_sk(sk);
-	struct sk_buff *skb;
-
-	if (tp->retrans_out)
-		return true;
-
-	skb = tcp_write_queue_head(sk);
-	if (unlikely(skb && TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS))
-		return true;
-
-	return false;
-}
-
 /* Undo during loss recovery after partial ACK or using F-RTO. */
 static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
 {
@@ -5229,7 +5231,7 @@ slow_path:
 	if (len < (th->doff << 2) || tcp_checksum_complete_user(sk, skb))
 		goto csum_error;
 
-	if (!th->ack && !th->rst)
+	if (!th->ack && !th->rst && !th->syn)
 		goto discard;
 
 	/*
@@ -5648,7 +5650,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 			goto discard;
 	}
 
-	if (!th->ack && !th->rst)
+	if (!th->ack && !th->rst && !th->syn)
 		goto discard;
 
 	if (!tcp_validate_incoming(sk, skb, th, 0))