tcp: avoid spurious SYN flood detection at listen() time

At listen() time, there is a small window where listener is visible with a zero backlog, triggering a spurious "Possible SYN flooding on port" message. Nothing prevents us from setting the correct backlog. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
mariux64 · Oct 15, 2015 · f985c65 · f985c65
1 parent c2f34a6
commit f985c65
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Showing 2 changed files with 3 additions and 3 deletions.
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
@@ -312,7 +312,7 @@ static inline unsigned int inet_csk_listen_poll(const struct sock *sk)
 			(POLLIN | POLLRDNORM) : 0;
 }
 
-int inet_csk_listen_start(struct sock *sk, const int nr_table_entries);
+int inet_csk_listen_start(struct sock *sk, int backlog);
 void inet_csk_listen_stop(struct sock *sk);
 
 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr);

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
@@ -727,14 +727,14 @@ void inet_csk_prepare_forced_close(struct sock *sk)
 }
 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
 
-int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
+int inet_csk_listen_start(struct sock *sk, int backlog)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct inet_sock *inet = inet_sk(sk);
 
 	reqsk_queue_alloc(&icsk->icsk_accept_queue);
 
-	sk->sk_max_ack_backlog = 0;
+	sk->sk_max_ack_backlog = backlog;
 	sk->sk_ack_backlog = 0;
 	inet_csk_delack_init(sk);