From 12d483a14899979a0e800657d9ead33175fae498 Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Tue, 24 Nov 2020 20:54:07 +0000
Subject: [PATCH] Don't advertise ext-info-[cs] during rekeys.

Apart from being pointless, it also triggers a bug in OpenSSH pre-8.1
that causes it to send a repeat EXT_INFO after the rekey concludes,
which trips our quite draconian check for whether EXT_INFO has been
sent at the right time.

The OpenSSH bug: https://bugzilla.mindrot.org/show_bug.cgi?id=2929
---
 ssh2transport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ssh2transport.c b/ssh2transport.c
index 3d1d7abb..e9b17fa4 100644
--- a/ssh2transport.c
+++ b/ssh2transport.c
@@ -837,7 +837,7 @@ static void ssh2_write_kexinit_lists(
                 add_to_commasep(list, kexlists[i][j].name);
             }
         }
-        if (i == KEXLIST_KEX) {
+        if (i == KEXLIST_KEX && first_time) {
             if (our_hostkeys)          /* we're the server */
                 add_to_commasep(list, "ext-info-s");
             else                       /* we're the client */