From: Mark Andrews <marka@isc.org>
Date: Tue, 10 Dec 2019 02:16:58 +0000 (+1100)
Subject: address deadlock introduced in cd2469d3cdbc211ecf8a82c76c1a0a1c4a545fec
X-Git-Tag: v9.15.7~16^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fd52417f712dedc6caec64c43969450fdd41b352;p=thirdparty%2Fbind9.git

address deadlock introduced in cd2469d3cdbc211ecf8a82c76c1a0a1c4a545fec
---

diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index d1814270134..97084c7af33 100644
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -164,7 +164,7 @@ typedef isc_rwlock_t nodelock_t;
 #define NODE_LOCK(l, t)         RWLOCK((l), (t))
 #define NODE_UNLOCK(l, t)       RWUNLOCK((l), (t))
 #define NODE_TRYUPGRADE(l)      isc_rwlock_tryupgrade(l)
-#define NODE_DOWNGRADE(l)   isc_rwlock_downgrade(l)
+#define NODE_DOWNGRADE(l)       isc_rwlock_downgrade(l)
 
 /*%
  * Whether to rate-limit updating the LRU to avoid possible thread contention.
@@ -6837,9 +6837,10 @@ subtractrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
 	 * this is deferred until closeversion() is called.
 	 */
 	if (result == ISC_R_SUCCESS && version == NULL && !IS_CACHE(rbtdb)) {
-		RBTDB_LOCK(&rbtdb->lock, isc_rwlocktype_write);
-		iszonesecure(db, rbtdb->current_version, rbtdb->origin_node);
-		RBTDB_UNLOCK(&rbtdb->lock, isc_rwlocktype_write);
+		RBTDB_LOCK(&rbtdb->lock, isc_rwlocktype_read);
+		version = rbtdb->current_version;
+		RBTDB_UNLOCK(&rbtdb->lock, isc_rwlocktype_read);
+		iszonesecure(db, version, rbtdb->origin_node);
 	}
 
 	return (result);
@@ -6895,9 +6896,10 @@ deleterdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
 	 * this is deferred until closeversion() is called.
 	 */
 	if (result == ISC_R_SUCCESS && version == NULL && !IS_CACHE(rbtdb)) {
-		RBTDB_LOCK(&rbtdb->lock, isc_rwlocktype_write);
-		iszonesecure(db, rbtdb->current_version, rbtdb->origin_node);
-		RBTDB_UNLOCK(&rbtdb->lock, isc_rwlocktype_write);
+		RBTDB_LOCK(&rbtdb->lock, isc_rwlocktype_read);
+		version = rbtdb->current_version;
+		RBTDB_UNLOCK(&rbtdb->lock, isc_rwlocktype_read);
+		iszonesecure(db, version, rbtdb->origin_node);
 	}
 
 	return (result);
@@ -7329,9 +7331,12 @@ endload(dns_db_t *db, dns_rdatacallbacks_t *callbacks) {
 	 * zone key, we consider the zone secure.
 	 */
 	if (! IS_CACHE(rbtdb) && rbtdb->origin_node != NULL) {
-		iszonesecure(db, rbtdb->current_version, rbtdb->origin_node);
+		dns_dbversion_t *version = rbtdb->current_version;
+		RBTDB_UNLOCK(&rbtdb->lock, isc_rwlocktype_write);
+		iszonesecure(db, version, rbtdb->origin_node);
+	} else {
+		RBTDB_UNLOCK(&rbtdb->lock, isc_rwlocktype_write);
 	}
-	RBTDB_UNLOCK(&rbtdb->lock, isc_rwlocktype_write);
 
 	callbacks->add = NULL;
 	callbacks->add_private = NULL;