tcp/dccp: fix behavior of stale SYN_RECV request sockets
When a TCP/DCCP listener is closed, its pending SYN_RECV request sockets
become stale, meaning 3WHS can not complete.
But current behavior is wrong :
incoming packets finding such stale sockets are dropped.
We need instead to cleanup the request socket and perform another
lookup :
- Incoming ACK will give a RST answer,
- SYN rtx might find another listener if available.
- We expedite cleanup of request sockets and old listener socket.
Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 2887c84..7ce1c57 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1363,6 +1363,7 @@
th = tcp_hdr(skb);
hdr = ipv6_hdr(skb);
+lookup:
sk = __inet6_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest,
inet6_iif(skb));
if (!sk)
@@ -1382,8 +1383,12 @@
reqsk_put(req);
goto discard_it;
}
- if (sk->sk_state == TCP_LISTEN)
+ if (likely(sk->sk_state == TCP_LISTEN)) {
nsk = tcp_check_req(sk, skb, req, false);
+ } else {
+ inet_csk_reqsk_queue_drop(sk, req);
+ goto lookup;
+ }
if (!nsk) {
reqsk_put(req);
goto discard_it;