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))