From: Mark Andrews <marka@isc.org>
Date: Thu, 4 Jan 2007 05:44:20 +0000 (+0000)
Subject: 2124.   [bug]           It was possible to dereference a freed fetch
X-Git-Tag: v9.3.2^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=774e2ffe705e24d7eacd9c81780b3cd404ec0da7;p=thirdparty%2Fbind9.git

2124.   [bug]           It was possible to dereference a freed fetch
                        context. [RT #16584]
---

diff --git a/CHANGES b/CHANGES
index 3f840882c14..e6fe3824a85 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,5 @@
+2124.	[bug]		It was possible to dereference a freed fetch
+			context. [RT #16584]
 
 	--- 9.3.2-WFB-4 released ---
 
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 7c8c7758665..74cda8df931 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: resolver.c,v 1.218.2.18.4.56.2.2 2006/08/03 23:07:37 marka Exp $ */
+/* $Id: resolver.c,v 1.218.2.18.4.56.2.3 2007/01/04 05:44:20 marka Exp $ */
 
 #include <config.h>
 
@@ -215,6 +215,11 @@ struct fetchctx {
 	dns_name_t 			nsname; 
 	dns_fetch_t *			nsfetch;
 	dns_rdataset_t			nsrrset;
+
+	/*%
+	 * Number of queries that reference this context.
+	 */
+	unsigned int			nqueries;
 };
 
 #define FCTX_MAGIC			ISC_MAGIC('F', '!', '!', '!')
@@ -348,6 +353,7 @@ static isc_result_t ncache_adderesult(dns_message_t *message,
 				      dns_rdataset_t *ardataset,
 				      isc_result_t *eresultp);
 static void validated(isc_task_t *task, isc_event_t *event); 
+static void maybe_destroy(fetchctx_t *fctx);
 
 static isc_result_t
 valcreate(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo, dns_name_t *name,
@@ -513,6 +519,9 @@ resquery_destroy(resquery_t **queryp) {
 
 	INSIST(query->tcpsocket == NULL);
 
+	query->fctx->nqueries--;
+	if (SHUTTINGDOWN(query->fctx))
+		maybe_destroy(query->fctx);	/* Locks bucket. */
 	query->magic = 0;
 	isc_mem_put(query->mctx, query, sizeof(*query));
 	*queryp = NULL;
@@ -1084,6 +1093,7 @@ fctx_query(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo,
 	}
 
 	ISC_LIST_APPEND(fctx->queries, query, link);
+	query->fctx->nqueries++;
 
 	return (ISC_R_SUCCESS);
 
@@ -1530,7 +1540,7 @@ fctx_finddone(isc_task_t *task, isc_event_t *event) {
 			want_done = ISC_TRUE;
 		}
 	} else if (SHUTTINGDOWN(fctx) && fctx->pending == 0 &&
-		   ISC_LIST_EMPTY(fctx->validators)) {
+		   fctx->nqueries == 0 && ISC_LIST_EMPTY(fctx->validators)) {
 		bucketnum = fctx->bucketnum;
 		LOCK(&res->buckets[bucketnum].lock);
 		/*
@@ -2384,8 +2394,8 @@ fctx_destroy(fetchctx_t *fctx) {
 	REQUIRE(ISC_LIST_EMPTY(fctx->finds));
 	REQUIRE(ISC_LIST_EMPTY(fctx->altfinds));
 	REQUIRE(fctx->pending == 0);
-	REQUIRE(ISC_LIST_EMPTY(fctx->validators));
 	REQUIRE(fctx->references == 0);
+	REQUIRE(ISC_LIST_EMPTY(fctx->validators));
 
 	FCTXTRACE("destroy");
 
@@ -2559,7 +2569,7 @@ fctx_doshutdown(isc_task_t *task, isc_event_t *event) {
 	}
 
 	if (fctx->references == 0 && fctx->pending == 0 &&
-	    ISC_LIST_EMPTY(fctx->validators))
+	    fctx->nqueries == 0 && ISC_LIST_EMPTY(fctx->validators))
 		bucket_empty = fctx_destroy(fctx);
 
 	UNLOCK(&res->buckets[bucketnum].lock);
@@ -2600,6 +2610,7 @@ fctx_start(isc_task_t *task, isc_event_t *event) {
 		 * pending ADB finds and no pending validations.
 		 */
 		INSIST(fctx->pending == 0);
+		INSIST(fctx->nqueries == 0);
 		INSIST(ISC_LIST_EMPTY(fctx->validators));
 		if (fctx->references == 0) {
 			/*
@@ -2761,6 +2772,7 @@ fctx_create(dns_resolver_t *res, dns_name_t *name, dns_rdatatype_t type,
 	fctx->restarts = 0;
 	fctx->timeouts = 0;
 	fctx->attributes = 0;
+	fctx->nqueries = 0;
 
 	dns_name_init(&fctx->nsname, NULL);
 	fctx->nsfetch = NULL;
@@ -3086,7 +3098,8 @@ maybe_destroy(fetchctx_t *fctx) {
 
 	REQUIRE(SHUTTINGDOWN(fctx));
 
-	if (fctx->pending != 0 || !ISC_LIST_EMPTY(fctx->validators))
+	if (fctx->pending != 0 || fctx->nqueries != 0 ||
+	    !ISC_LIST_EMPTY(fctx->validators))
 		return;
 
 	bucketnum = fctx->bucketnum;
@@ -6346,7 +6359,8 @@ dns_resolver_destroyfetch(dns_fetch_t **fetchp) {
 		/*
 		 * No one cares about the result of this fetch anymore.
 		 */
-		if (fctx->pending == 0 && ISC_LIST_EMPTY(fctx->validators) &&
+		if (fctx->pending == 0 && fctx->nqueries == 0 &&
+		    ISC_LIST_EMPTY(fctx->validators) &&
 		    SHUTTINGDOWN(fctx)) {
 			/*
 			 * This fctx is already shutdown; we were just