[PATCH net] ipv6: tcp: fix flowlabels reflection for RST packets

[Eric Dumazet <edumazet@google.com>]

In 323a53c41292 ("ipv6: tcp: enable flowlabel reflection in some RST packets")
and 50a8accf1062 ("ipv6: tcp: send consistent flowlabel in TIME_WAIT state")
we took care of IPv6 flowlabel reflections for two cases.

This patch takes care of the remaining case, when the RST packet
is sent on behalf of a 'full' socket.

In Marek use case, this was a socket in TCP_CLOSE state.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Marek Majkowski <marek@cloudflare.com>
Tested-by: Marek Majkowski <marek@cloudflare.com>
---
 net/ipv6/tcp_ipv6.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index d56a9019a0feb5a34312ec353c555f44b8c09b3d..5da069e91cacca4e84a3e41dae4746c9d38fcc46 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -984,8 +984,13 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
 
 	if (sk) {
 		oif = sk->sk_bound_dev_if;
-		if (sk_fullsock(sk))
+		if (sk_fullsock(sk)) {
+			const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
+
 			trace_tcp_send_reset(sk, skb);
+			if (np->repflow)
+				label = ip6_flowlabel(ipv6h);
+		}
 		if (sk->sk_state == TCP_TIME_WAIT)
 			label = cpu_to_be32(inet_twsk(sk)->tw_flowlabel);
 	} else {
-- 
2.22.0.410.gd8fdbe21b5-goog