From: Willy Tarreau <w@1wt.eu>
Date: Thu, 28 May 2020 16:07:10 +0000 (+0200)
Subject: BUG/MINOR: nameservers: fix error handling in parsing of resolv.conf
X-Git-Tag: v2.2-dev9~174
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=78675252fb6ce195c145afd2862fa53087bf585f;p=thirdparty%2Fhaproxy.git

BUG/MINOR: nameservers: fix error handling in parsing of resolv.conf

In issue #657, Coverity found a bug in the "nameserver" parser for the
resolv.conf when "parse-resolv-conf" is set. What happens is that if an
unparsable address appears on a "nameserver" line, it will destroy the
previously allocated pointer before reporting the warning, then the next
"nameserver" line will dereference it again and wlil cause a crash. If
the faulty nameserver is the last one, it will only be a memory leak.
Let's just make sure we preserve the pointer when handling the error.
The patch also fixes a typo in the warning.

The bug was introduced in 1.9 with commit 44e609bfa ("MINOR: dns:
Implement `parse-resolv-conf` directive") so the fix needs to be backported
up to 1.9 or 2.0.
---

diff --git a/src/cfgparse.c b/src/cfgparse.c
index 63e150f388..2f0688a4bc 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -1130,9 +1130,8 @@ int cfg_parse_resolvers(const char *file, int linenum, char **args, int kwm)
 				continue;
 
 			memset(sk, 0, sizeof(*sk));
-			sk = str2ip2(address, sk, 1);
-			if (!sk) {
-				ha_warning("parsing [/etc/resolv.conf:%d] : address '%s' could not be recognized, namerserver will be excluded.\n",
+			if (!str2ip2(address, sk, 1)) {
+				ha_warning("parsing [/etc/resolv.conf:%d] : address '%s' could not be recognized, nameserver will be excluded.\n",
 					   resolv_linenum, address);
 				err_code |= ERR_WARN;
 				continue;