Address race between zone_maintenance and dns_zone_setview_helper

There was a possible NULL dereference due to data race between accessing
zone->view and zone->view->adb.

(cherry picked from commit 67c8f7329de48587c6322e2f077b2b7f476ef41f)

diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index 19740fd34cb89596fc721b1097734b591fee1bc6..c8e880f4c1d180bf81ea35a417aeca1ee9fd4a88 100644 (file)
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -10133,7 +10133,7 @@ zone_maintenance(dns_zone_t *zone) {
        const char me[] = "zone_maintenance";
        isc_time_t now;
        isc_result_t result;
-       bool dumping, load_pending;
+       bool dumping, load_pending, viewok;
 
        REQUIRE(DNS_ZONE_VALID(zone));
        ENTER;
@@ -10156,8 +10156,12 @@ zone_maintenance(dns_zone_t *zone) {
         * adb or resolver will be NULL, and we had better not try
         * to do further maintenance on it.
         */
-       if (zone->view == NULL || zone->view->adb == NULL)
+       LOCK_ZONE(zone);
+       viewok = (zone->view != NULL && zone->view->adb != NULL);
+       UNLOCK_ZONE(zone);
+       if (!viewok) {
                return;
+       }
 
        TIME_NOW(&now);