---

yaml
---
r: 348025
b: refs/heads/master
c: c3ae62a
h: refs/heads/master
i:
  348023: 35d9d35
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3d0dcfbd8fa2a1e63fabb5f8edac8b8a27860d98
+refs/heads/master: c3ae62af8e755ea68380fb5ce682e60079a4c388

trunk/net/ipv4/tcp_input.c

@@ -5543,6 +5543,9 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
 	if (len < (th->doff << 2) || tcp_checksum_complete_user(sk, skb))
 		goto csum_error;
 
+	if (!th->ack)
+		goto discard;
+
 	/*
 	 *	Standard slow path.
 	 */
@@ -5551,7 +5554,7 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
 		return 0;
 
 step5:
-	if (th->ack && tcp_ack(sk, skb, FLAG_SLOWPATH) < 0)
+	if (tcp_ack(sk, skb, FLAG_SLOWPATH) < 0)
 		goto discard;
 
 	/* ts_recent update must be made after we are sure that the packet
@@ -5984,11 +5987,15 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 		if (tcp_check_req(sk, skb, req, NULL, true) == NULL)
 			goto discard;
 	}
+
+	if (!th->ack)
+		goto discard;
+
 	if (!tcp_validate_incoming(sk, skb, th, 0))
 		return 0;
 
 	/* step 5: check the ACK field */
-	if (th->ack) {
+	if (true) {
 		int acceptable = tcp_ack(sk, skb, FLAG_SLOWPATH) > 0;
 
 		switch (sk->sk_state) {
@@ -6138,8 +6145,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 			}
 			break;
 		}
-	} else
-		goto discard;
+	}
 
 	/* ts_recent update must be made after we are sure that the packet
 	 * is in window.