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.

diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index 36bcacc6c8579d78f0d56deea03c4f7c6bd4382f..5cfc2bf4c24b4a37a1f7782c56c83a75e20eb2d2 100644 (file)
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -10857,7 +10857,7 @@ 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;
@@ -10880,7 +10880,10 @@ 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;
        }