From: Mark Andrews <marka@isc.org>
Date: Mon, 9 Mar 2020 00:33:05 +0000 (+1100)
Subject: Silence missing unlock from Coverity.
X-Git-Tag: v9.17.1~48^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8dd8d48c9f679b58c244cbe09637404905a00af6;p=thirdparty%2Fbind9.git

Silence missing unlock from Coverity.

Save 'i' to 'locknum' and use that rather than using
'header->node->locknum' when performing the deferred
unlock as 'header->node->locknum' can theoretically be
different to 'i'.
---

diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index 9c4391a9cc1..a4522c1dd80 100644
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -8075,7 +8075,7 @@ getsigningtime(dns_db_t *db, dns_rdataset_t *rdataset, dns_name_t *foundname) {
 	rdatasetheader_t *header = NULL, *this;
 	unsigned int i;
 	isc_result_t result = ISC_R_NOTFOUND;
-	unsigned int locknum;
+	unsigned int locknum = 0;
 
 	REQUIRE(VALID_RBTDB(rbtdb));
 
@@ -8083,41 +8083,64 @@ getsigningtime(dns_db_t *db, dns_rdataset_t *rdataset, dns_name_t *foundname) {
 
 	for (i = 0; i < rbtdb->node_lock_count; i++) {
 		NODE_LOCK(&rbtdb->node_locks[i].lock, isc_rwlocktype_read);
+
+		/*
+		 * Find for the earliest signing time among all of the
+		 * heaps, each of which is covered by a different bucket
+		 * lock.
+		 */
 		this = isc_heap_element(rbtdb->heaps[i], 1);
 		if (this == NULL) {
+			/* Nothing found; unlock and try the next heap. */
 			NODE_UNLOCK(&rbtdb->node_locks[i].lock,
 				    isc_rwlocktype_read);
 			continue;
 		}
+
 		if (header == NULL) {
+			/*
+			 * Found a signing time: retain the bucket lock and
+			 * preserve the lock number so we can unlock it
+			 * later.
+			 */
 			header = this;
+			locknum = i;
 		} else if (resign_sooner(this, header)) {
-			locknum = header->node->locknum;
+			/*
+			 * Found an earlier signing time; release the
+			 * previous bucket lock and retain this one instead.
+			 */
 			NODE_UNLOCK(&rbtdb->node_locks[locknum].lock,
 				    isc_rwlocktype_read);
 			header = this;
+			locknum = i;
 		} else {
+			/*
+			 * Earliest signing time in this heap isn't
+			 * an improvement; unlock and try the next heap.
+			 */
 			NODE_UNLOCK(&rbtdb->node_locks[i].lock,
 				    isc_rwlocktype_read);
 		}
 	}
 
-	if (header == NULL) {
-		goto unlock;
-	}
-
-	bind_rdataset(rbtdb, header->node, header, 0, rdataset);
+	if (header != NULL) {
+		/*
+		 * Found something; pass back the answer and unlock
+		 * the bucket.
+		 */
+		bind_rdataset(rbtdb, header->node, header, 0, rdataset);
 
-	if (foundname != NULL) {
-		dns_rbt_fullnamefromnode(header->node, foundname);
-	}
+		if (foundname != NULL) {
+			dns_rbt_fullnamefromnode(header->node, foundname);
+		}
 
-	NODE_UNLOCK(&rbtdb->node_locks[header->node->locknum].lock,
-		    isc_rwlocktype_read);
+		NODE_UNLOCK(&rbtdb->node_locks[locknum].lock,
+			    isc_rwlocktype_read);
 
-	result = ISC_R_SUCCESS;
+		result = ISC_R_SUCCESS;
+	}
 
-unlock:
 	RWUNLOCK(&rbtdb->tree_lock, isc_rwlocktype_read);
 
 	return (result);