From: Ondřej Surý <ondrej@sury.org>
Date: Mon, 19 Apr 2021 07:25:14 +0000 (+0200)
Subject: Fix task timing race in setnsec3param()
X-Git-Tag: v9.17.13~55^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0127ba6472a210f7ca41bf18e5a5c9b015f20c6c;p=thirdparty%2Fbind9.git

Fix task timing race in setnsec3param()

When setnsec3param() is schedule from zone_postload() there's no
guarantee that `zone->db` is not `NULL` yet.  Thus when the
setnsec3param() is called, we need to check for `zone->db` existence and
reschedule the task, because calling `rss_post()` on a zone with empty
`.db` ends up with no-op (the function just returns).
---

diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index e0a94a6d00e..adfe082a4b9 100644
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -21119,6 +21119,22 @@ setnsec3param(isc_task_t *task, isc_event_t *event) {
 		 */
 		ISC_LIST_APPEND(zone->rss_post, event, ev_link);
 	} else {
+		bool rescheduled = false;
+		ZONEDB_LOCK(&zone->dblock, isc_rwlocktype_read);
+		/*
+		 * The zone is not yet fully loaded. Reschedule the event to
+		 * be picked up later. This turns this function into a busy
+		 * wait, but it only happens at startup.
+		 */
+		if (zone->db == NULL) {
+			rescheduled = true;
+			isc_task_send(task, &event);
+		}
+		ZONEDB_UNLOCK(&zone->dblock, isc_rwlocktype_read);
+		if (rescheduled) {
+			return;
+		}
+
 		rss_post(zone, event);
 	}
 	dns_zone_idetach(&zone);