From: Mark Andrews <marka@isc.org>
Date: Fri, 17 Sep 2021 02:55:07 +0000 (+1000)
Subject: Pause the dbiterator before calling dns_db_find
X-Git-Tag: v9.17.19~22^2~1
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4e1faa35d502cdaf9214e9f00407c9e06500d7c4;p=thirdparty%2Fbind9.git

Pause the dbiterator before calling dns_db_find

zone.c:integrity_checks() acquires a read lock while iterating the
zone database, and calls zone_check_mx() which acquires another
read lock. If another thread tries to acquire a write lock in the
meantime, it can deadlock. Calling dns_dbiterator_pause() to release
the first read lock prevents this.
---

diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index 5235e1b610d..7bd8c05c9b6 100644
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -3326,6 +3326,8 @@ integrity_checks(dns_zone_t *zone, dns_db_t *db) {
 			goto next;
 		}
 
+		dns_dbiterator_pause(dbiterator);
+
 		/*
 		 * Don't check the NS records at the origin.
 		 */