From: Christopher Faulet <cfaulet@haproxy.com>
Date: Wed, 22 Jul 2020 13:55:49 +0000 (+0200)
Subject: BUG/MEDIUM: dns: Release answer items when a DNS resolution is freed
X-Git-Tag: v2.3-dev2~36
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=010ab35a9118daf17a670fb2b42e40447f967f7c;p=thirdparty%2Fhaproxy.git

BUG/MEDIUM: dns: Release answer items when a DNS resolution is freed

When a DNS resolution is freed, the remaining items in .ar_list and .answer_list
are also released. It must be done to avoid a memory leak. And it is the last
chance to release these objects. I've honestly no idea if there is a better
place to release them earlier. But at least, there is no more leak.

This patch should solve the issue #222. It must be backported, at least, as far
as 2.0, and probably, with caution, as far as 1.8 or 1.7.
---

diff --git a/src/dns.c b/src/dns.c
index b38f58bed1..b53e3b6fbd 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -1573,6 +1573,7 @@ static struct dns_resolution *dns_pick_resolution(struct dns_resolvers *resolver
 static void dns_free_resolution(struct dns_resolution *resolution)
 {
 	struct dns_requester *req, *reqback;
+	struct dns_answer_item *item, *itemback;
 
 	/* clean up configuration */
 	dns_reset_resolution(resolution);
@@ -1584,6 +1585,16 @@ static void dns_free_resolution(struct dns_resolution *resolution)
 		req->resolution = NULL;
 	}
 
+	list_for_each_entry_safe(item, itemback, &resolution->response.ar_list, list) {
+		LIST_DEL(&item->list);
+		pool_free(dns_answer_item_pool, item);
+	}
+
+	list_for_each_entry_safe(item, itemback, &resolution->response.answer_list, list) {
+		LIST_DEL(&item->list);
+		pool_free(dns_answer_item_pool, item);
+	}
+
 	LIST_DEL(&resolution->list);
 	pool_free(dns_resolution_pool, resolution);
 }