From: claudio <claudio@openbsd.org>
Date: Tue, 10 Oct 2023 14:36:28 +0000 (+0000)
Subject: When rewriting community_writebuf() the handling of non-transitive
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=578f8c8857308c1dca3745fe0bae04d8bd0556b8;p=openbsd

When rewriting community_writebuf() the handling of non-transitive
ext-communities was put into the wrong place in the loop finding
start, end and number of communities to dump. As a result the end
pointer for regular communities can point at an ext-community and
with that the COMMUNITY attribute written includes unexpected extra
bytes. This in turn causes the peer to send a NOTIFICATION error
and to terminate the session.

Fix for -portable issue #64 reported by Pier Carlo Chiodi (pierky)
OK tb@
---

diff --git a/usr.sbin/bgpd/rde_community.c b/usr.sbin/bgpd/rde_community.c
index d7a8717f475..803a374e8b6 100644
--- a/usr.sbin/bgpd/rde_community.c
+++ b/usr.sbin/bgpd/rde_community.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rde_community.c,v 1.13 2023/07/12 14:45:43 claudio Exp $ */
+/*	$OpenBSD: rde_community.c,v 1.14 2023/10/10 14:36:28 claudio Exp $ */
 
 /*
  * Copyright (c) 2019 Claudio Jeker <claudio@openbsd.org>
@@ -556,10 +556,9 @@ community_writebuf(struct rde_community *comm, uint8_t type, int ebgp,
 	start = -1;
 	for (l = 0; l < comm->nentries; l++) {
 		cp = &comm->communities[l];
-
-		if (ebgp && non_transitive_ext_community(cp))
-			continue;
 		if ((uint8_t)cp->flags == t) {
+			if (ebgp && non_transitive_ext_community(cp))
+				continue;
 			num++;
 			if (start == -1)
 				start = l;