From: claudio <claudio@openbsd.org>
Date: Thu, 20 Sep 2018 07:41:25 +0000 (+0000)
Subject: Fix the empty aspath segments check. seg_size is never 0, this needs to use
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=d04df93831fe37af372e74dda5413ce59c0edfb0;p=openbsd

Fix the empty aspath segments check. seg_size is never 0, this needs to use
seg_len instead. Since seg_len is known early move the check up.
Found while hunting for the other bug in aspath_verify.
---

diff --git a/usr.sbin/bgpd/util.c b/usr.sbin/bgpd/util.c
index 0c01b54e2b7..c60c7241351 100644
--- a/usr.sbin/bgpd/util.c
+++ b/usr.sbin/bgpd/util.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.36 2018/09/20 07:37:06 claudio Exp $ */
+/*	$OpenBSD: util.c,v 1.37 2018/09/20 07:41:25 claudio Exp $ */
 
 /*
  * Copyright (c) 2006 Claudio Jeker <claudio@openbsd.org>
@@ -459,6 +459,10 @@ aspath_verify(void *data, u_int16_t len, int as4byte)
 		seg_type = seg[0];
 		seg_len = seg[1];
 
+		if (seg_len == 0)
+			/* empty aspath segments are not allowed */
+			return (AS_ERR_BAD);
+
 		/*
 		 * BGP confederations should not show up but consider them
 		 * as a soft error which invalidates the path but keeps the
@@ -475,10 +479,6 @@ aspath_verify(void *data, u_int16_t len, int as4byte)
 		if (seg_size > len)
 			return (AS_ERR_LEN);
 
-		if (seg_size == 0)
-			/* empty aspath segments are not allowed */
-			return (AS_ERR_BAD);
-
 		/* RFC 7607 - AS 0 is considered malformed */
 		ptr = seg + 2;
 		for (pos = 0; pos < seg_len; pos++) {