From ebdd46367ce1acba235013d97e362b8677b538d5 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Wed, 19 Mar 2025 17:57:45 +0100 Subject: tcp: Flush socket before checking for more data in active close state MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Otherwise, if all the pending data is acknowledged: - tcp_update_seqack_from_tap() updates the current tap-side ACK sequence (conn->seq_ack_from_tap) - next, we compare the sequence we sent (conn->seq_to_tap) to the ACK sequence (conn->seq_ack_from_tap) in tcp_data_from_sock() to understand if there's more data we can send. If they match, we conclude that we haven't sent any of that data, and keep re-sending it. We need, instead, to flush the socket (drop acknowledged data) before calling tcp_update_seqack_from_tap(), so that once we update conn->seq_ack_from_tap, we can be sure that all data until there is gone from the socket. Link: https://bugs.passt.top/show_bug.cgi?id=114 Reported-by: Marek Marczykowski-Górecki Fixes: 30f1e082c3c0 ("tcp: Keep updating window and checking for socket data after FIN from guest") Signed-off-by: Stefano Brivio Reviewed-by: David Gibson --- tcp.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tcp.c b/tcp.c index 68af43d..fa1d885 100644 --- a/tcp.c +++ b/tcp.c @@ -2049,6 +2049,7 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af, /* Established connections not accepting data from tap */ if (conn->events & TAP_FIN_RCVD) { + tcp_sock_consume(conn, ntohl(th->ack_seq)); tcp_update_seqack_from_tap(c, conn, ntohl(th->ack_seq)); tcp_tap_window_update(conn, ntohs(th->window)); tcp_data_from_sock(c, conn); -- cgit v1.2.3