From: Matthijs Mekking <matthijs@isc.org>
Date: Mon, 21 Jun 2021 09:36:50 +0000 (+0200)
Subject: Fix deadlock issue with key-directory and in-view
X-Git-Tag: v9.17.16~27^2~1
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=42c601ae14cd2b9526ae54d674a7d3f47dda969c;p=thirdparty%2Fbind9.git

Fix deadlock issue with key-directory and in-view

When locking key files for a zone, we iterate over all the views and
lock a mutex inside the zone structure. However, if we envounter an
in-view zone, we will try to lock the key files twice, one time for
the home view and one time for the in-view view. This will lead to
a deadlock because one thread is trying to get the same lock twice.
---

diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index 8497e23c0b9..0755baf6364 100644
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -6395,6 +6395,17 @@ dns__zone_lockunlock_keyfiles(dns_zone_t *zone, bool lock) {
 		if (ret == ISC_R_SUCCESS) {
 			INSIST(DNS_ZONE_VALID(z));
 
+			/*
+			 * Skip in-view zones, in other words if the view
+			 * pointer is not the same as the zone view pointer:
+			 * 'in-view' zones can be part of another view,
+			 * while they also have their own home view.
+			 */
+			if (v != z->view) {
+				dns_zone_detach(&z);
+				continue;
+			}
+
 			/* WMM check if policy is the same? */
 			if (lock) {
 				LOCK_KEYFILES(z);