[PATCH RFC] tcp: diag: Also support for FIN_WAIT1 sockets for tcp_abort()

[Leonard Crestez <cdleonard@gmail.com>]

Aborting tcp connections via ss -K doesn't work in TCP_FIN_WAIT1 state,
this happens because the SOCK_DEAD flag is set. Fix by ignoring that flag
for this special case.

Signed-off-by: Leonard Crestez <cdleonard@gmail.com>

---
 net/ipv4/tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

I tested that this fixes the problem but not certain about correctness.

Support for TCP_TIME_WAIT was added recently but it doesn't fix
TCP_FIN_WAIT1.

See: https://lore.kernel.org/netdev/20220627121038.226500-1-edumazet@google.com/

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index d9dd998fdb76..215e7d3fed13 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4661,11 +4661,11 @@ int tcp_abort(struct sock *sk, int err)
 
 	/* Don't race with BH socket closes such as inet_csk_listen_stop. */
 	local_bh_disable();
 	bh_lock_sock(sk);
 
-	if (!sock_flag(sk, SOCK_DEAD)) {
+	if (sk->sk_state == TCP_FIN_WAIT1 || !sock_flag(sk, SOCK_DEAD)) {
 		sk->sk_err = err;
 		/* This barrier is coupled with smp_rmb() in tcp_poll() */
 		smp_wmb();
 		sk_error_report(sk);
 		if (tcp_need_reset(sk->sk_state))
-- 
2.25.1