Clear the pointer to destroyed object early using the semantic patch

Also disable the semantic patch as the code needs tweaks here and there because some destroy functions might not destroy the object and return early if the object is still in use.
2025-08-22 10:10:06 +00:00 · 2020-02-08 04:37:54 -08:00 · 2020-02-08 04:37:54 -08:00 · bc1d4c9cb4
commit bc1d4c9cb4
parent b97d003033
64 changed files with 94 additions and 144 deletions
--- a/bin/dnssec/dnssec-cds.c
+++ b/bin/dnssec/dnssec-cds.c
@ -574,6 +574,7 @@ match_keyset_dsset(dns_rdataset_t *keyset, dns_rdataset_t *dsset,
 static void
 free_keytable(keyinfo_t **keytable_p) {
 	keyinfo_t *keytable = *keytable_p;
+	*keytable_p = NULL;
 	keyinfo_t *ki;
 	int i;

@ -585,7 +586,6 @@ free_keytable(keyinfo_t **keytable_p) {
 	}

 	isc_mem_put(mctx, keytable, sizeof(keyinfo_t) * nkey);
-	*keytable_p = NULL;
 }

 /*
--- a/bin/named/controlconf.c
+++ b/bin/named/controlconf.c
@ -1477,10 +1477,10 @@ named_controls_create(named_server_t *server, named_controls_t **ctrlsp) {
 void
 named_controls_destroy(named_controls_t **ctrlsp) {
 	named_controls_t *controls = *ctrlsp;
+	*ctrlsp = NULL;

 	REQUIRE(ISC_LIST_EMPTY(controls->listeners));

 	isccc_symtab_destroy(&controls->symtab);
 	isc_mem_put(controls->server->mctx, controls, sizeof(*controls));
-	*ctrlsp = NULL;
 }
--- a/bin/nsupdate/nsupdate.c
+++ b/bin/nsupdate/nsupdate.c
@ -313,6 +313,7 @@ check_result(isc_result_t result, const char *msg) {
 static char *
 nsu_strsep(char **stringp, const char *delim) {
 	char *string = *stringp;
+	*stringp = NULL;
 	char *s;
 	const char *d;
 	char sc, dc;
@ -340,7 +341,6 @@ nsu_strsep(char **stringp, const char *delim) {
 			}
 		}
 	}
-	*stringp = NULL;
 	return (string);
 }

--- a/bin/tests/system/dyndb/driver/instance.c
+++ b/bin/tests/system/dyndb/driver/instance.c
@ -178,6 +178,7 @@ destroy_sample_instance(sample_instance_t **instp) {
 	REQUIRE(instp != NULL);

 	inst = *instp;
+	*instp = NULL;
 	if (inst == NULL)
 		return;

@ -195,6 +196,4 @@ destroy_sample_instance(sample_instance_t **instp) {
 	isc_task_detach(&inst->task);

 	MEM_PUT_AND_DETACH(inst);
-
-	*instp = NULL;
 }
--- a/cocci/null-the-pointer-early.disabled
+++ b/cocci/null-the-pointer-early.disabled
--- a/lib/dns/adb.c
+++ b/lib/dns/adb.c
@ -2293,8 +2293,8 @@ check_expire_name(dns_adbname_t **namep, isc_stdtime_t now) {
 	/*
 	 * The name is empty.  Delete it.
 	 */
-	result = kill_name(&name, DNS_EVENT_ADBEXPIRED);
 	*namep = NULL;
+	result = kill_name(&name, DNS_EVENT_ADBEXPIRED);

 	/*
 	 * Our caller, or one of its callers, will be calling check_exit() at
@ -2379,13 +2379,13 @@ check_expire_entry(dns_adb_t *adb, dns_adbentry_t **entryp, isc_stdtime_t now)
 	/*
 	 * The entry is not in use.  Delete it.
 	 */
+	*entryp = NULL;
 	DP(DEF_LEVEL, "killing entry %p", entry);
 	INSIST(ISC_LINK_LINKED(entry, plink));
 	result = unlink_entry(adb, entry);
 	free_adbentry(adb, &entry);
 	if (result)
 		dec_adb_irefcnt(adb);
-	*entryp = NULL;
 	return (result);
 }

@ -4604,11 +4604,11 @@ dns_adb_freeaddrinfo(dns_adb_t *adb, dns_adbaddrinfo_t **addrp) {
 	REQUIRE(DNS_ADB_VALID(adb));
 	REQUIRE(addrp != NULL);
 	addr = *addrp;
+	*addrp = NULL;
 	REQUIRE(DNS_ADBADDRINFO_VALID(addr));
 	entry = addr->entry;
 	REQUIRE(DNS_ADBENTRY_VALID(entry));

-	*addrp = NULL;
 	overmem = isc_mem_isovermem(adb->mctx);

 	bucket = addr->entry->lock_bucket;
--- a/lib/dns/badcache.c
+++ b/lib/dns/badcache.c
@ -91,6 +91,7 @@ dns_badcache_destroy(dns_badcache_t **bcp) {

 	REQUIRE(bcp != NULL && *bcp != NULL);
 	bc = *bcp;
+	*bcp = NULL;

 	dns_badcache_flush(bc);

@ -98,7 +99,6 @@ dns_badcache_destroy(dns_badcache_t **bcp) {
 	isc_mutex_destroy(&bc->lock);
 	isc_mem_put(bc->mctx, bc->table, sizeof(dns_bcentry_t *) * bc->size);
 	isc_mem_putanddetach(&bc->mctx, bc, sizeof(dns_badcache_t));
-	*bcp = NULL;
 }

 static isc_result_t
--- a/lib/dns/byaddr.c
+++ b/lib/dns/byaddr.c
@ -266,6 +266,7 @@ dns_byaddr_destroy(dns_byaddr_t **byaddrp) {

 	REQUIRE(byaddrp != NULL);
 	byaddr = *byaddrp;
+	*byaddrp = NULL;
 	REQUIRE(VALID_BYADDR(byaddr));
 	REQUIRE(byaddr->event == NULL);
 	REQUIRE(byaddr->task == NULL);
@ -274,6 +275,4 @@ dns_byaddr_destroy(dns_byaddr_t **byaddrp) {
 	isc_mutex_destroy(&byaddr->lock);
 	byaddr->magic = 0;
 	isc_mem_putanddetach(&byaddr->mctx, byaddr, sizeof(*byaddr));
-
-	*byaddrp = NULL;
 }
--- a/lib/dns/cache.c
+++ b/lib/dns/cache.c
@ -404,8 +404,8 @@ dns_cache_detach(dns_cache_t **cachep) {

 	REQUIRE(cachep != NULL);
 	cache = *cachep;
-	REQUIRE(VALID_CACHE(cache));
 	*cachep = NULL;
+	REQUIRE(VALID_CACHE(cache));

 	if (isc_refcount_decrement(&cache->references) == 1) {
 		cache->cleaner.overmem = false;
--- a/lib/dns/catz.c
+++ b/lib/dns/catz.c
@ -264,9 +264,8 @@ dns_catz_entry_detach(dns_catz_zone_t *zone, dns_catz_entry_t **entryp) {
 	REQUIRE(DNS_CATZ_ZONE_VALID(zone));
 	REQUIRE(entryp != NULL);
 	entry = *entryp;
-	REQUIRE(DNS_CATZ_ENTRY_VALID(entry));
-
 	*entryp = NULL;
+	REQUIRE(DNS_CATZ_ENTRY_VALID(entry));

 	if (isc_refcount_decrement(&entry->refs) == 1) {
 		isc_mem_t *mctx = zone->catzs->mctx;
--- a/lib/dns/client.c
+++ b/lib/dns/client.c
@ -734,14 +734,13 @@ putrdataset(isc_mem_t *mctx, dns_rdataset_t **rdatasetp) {

 	REQUIRE(rdatasetp != NULL);
 	rdataset = *rdatasetp;
+	*rdatasetp = NULL;
 	REQUIRE(rdataset != NULL);

 	if (dns_rdataset_isassociated(rdataset))
 		dns_rdataset_disassociate(rdataset);

 	isc_mem_put(mctx, rdataset, sizeof(*rdataset));
-
-	*rdatasetp = NULL;
 }

 static void
--- a/lib/dns/dbtable.c
+++ b/lib/dns/dbtable.c
@ -124,8 +124,8 @@ dns_dbtable_detach(dns_dbtable_t **dbtablep) {

 	REQUIRE(dbtablep != NULL);
 	dbtable = *dbtablep;
-	REQUIRE(VALID_DBTABLE(dbtable));
 	*dbtablep = NULL;
+	REQUIRE(VALID_DBTABLE(dbtable));

 	if (isc_refcount_decrement(&dbtable->references) == 1) {
 		dbtable_free(dbtable);
--- a/lib/dns/diff.c
+++ b/lib/dns/diff.c
@ -104,6 +104,7 @@ dns_difftuple_create(isc_mem_t *mctx,
 void
 dns_difftuple_free(dns_difftuple_t **tp) {
 	dns_difftuple_t *t = *tp;
+	*tp = NULL;
 	isc_mem_t *mctx;

 	REQUIRE(DNS_DIFFTUPLE_VALID(t));
@ -113,7 +114,6 @@ dns_difftuple_free(dns_difftuple_t **tp) {
 	mctx = t->mctx;
 	isc_mem_free(mctx, t);
 	isc_mem_detach(&mctx);
-	*tp = NULL;
 }

 isc_result_t
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@ -594,8 +594,9 @@ new_portentry(dns_dispatch_t *disp, in_port_t port) {
 */
 static void
 deref_portentry(dns_dispatch_t *disp, dispportentry_t **portentryp) {
-	dispportentry_t *portentry = *portentryp;
 	dns_qid_t *qid;
+	dispportentry_t *portentry = *portentryp;
+	*portentryp = NULL;

 	REQUIRE(disp->port_table != NULL);
 	REQUIRE(portentry != NULL);
@ -609,13 +610,6 @@ deref_portentry(dns_dispatch_t *disp, dispportentry_t **portentryp) {
 		isc_mempool_put(disp->portpool, portentry);
 		UNLOCK(&qid->lock);
 	}
-
-	/*
-	 * XXXWPK TODO: is it really necessary?
-	 * Set '*portentryp' to NULL inside the lock so that
-	 * dispsock->portentry does not change in socket_search.
-	 */
-	*portentryp = NULL;
 }

 /*%
@ -785,6 +779,7 @@ destroy_dispsocket(dns_dispatch_t *disp, dispsocket_t **dispsockp) {

 	REQUIRE(dispsockp != NULL && *dispsockp != NULL);
 	dispsock = *dispsockp;
+	*dispsockp = NULL;
 	REQUIRE(!ISC_LINK_LINKED(dispsock, link));

 	disp->nsockets--;
@ -803,8 +798,6 @@ destroy_dispsocket(dns_dispatch_t *disp, dispsocket_t **dispsockp) {
 	if (dispsock->task != NULL)
 		isc_task_detach(&dispsock->task);
 	isc_mempool_put(disp->mgr->spool, dispsock);
-
-	*dispsockp = NULL;
 }

 /*%
@ -2237,10 +2230,10 @@ qid_destroy(isc_mem_t *mctx, dns_qid_t **qidp) {

 	REQUIRE(qidp != NULL);
 	qid = *qidp;
+	*qidp = NULL;

 	REQUIRE(VALID_QID(qid));

-	*qidp = NULL;
 	qid->magic = 0;
 	isc_mem_put(mctx, qid->qid_table,
 		    qid->qid_nbuckets * sizeof(dns_displist_t));
@ -3632,14 +3625,13 @@ dns_dispatchset_destroy(dns_dispatchset_t **dsetp) {
 	REQUIRE(dsetp != NULL && *dsetp != NULL);

 	dset = *dsetp;
+	*dsetp = NULL;
 	for (i = 0; i < dset->ndisp; i++)
 		dns_dispatch_detach(&(dset->dispatches[i]));
 	isc_mem_put(dset->mctx, dset->dispatches,
 		    sizeof(dns_dispatch_t *) * dset->ndisp);
 	isc_mutex_destroy(&dset->lock);
 	isc_mem_putanddetach(&dset->mctx, dset, sizeof(dns_dispatchset_t));
-
-	*dsetp = NULL;
 }

 void
--- a/lib/dns/dnsrps.c
+++ b/lib/dns/dnsrps.c
@ -798,13 +798,13 @@ rpsdb_rdatasetiter_destroy(dns_rdatasetiter_t **iteratorp) {
 	isc_mem_t *mctx;

 	iterator = *iteratorp;
+	*iteratorp = NULL;
 	rpsdb = (rpsdb_t *)iterator->db;
 	REQUIRE(VALID_RPSDB(rpsdb));

 	mctx = iterator->db->mctx;
 	dns_db_detachnode(iterator->db, &iterator->node);
 	isc_mem_put(mctx, iterator, sizeof(rpsdb_rdatasetiter_t));
-	*iteratorp = NULL;
 }

 static isc_result_t
--- a/lib/dns/dnssec.c
+++ b/lib/dns/dnssec.c
@ -1285,10 +1285,10 @@ dns_dnsseckey_destroy(isc_mem_t *mctx, dns_dnsseckey_t **dkp) {

 	REQUIRE(dkp != NULL && *dkp != NULL);
 	dk = *dkp;
+	*dkp = NULL;
 	if (dk->key != NULL)
 		dst_key_free(&dk->key);
 	isc_mem_put(mctx, dk, sizeof(dns_dnsseckey_t));
-	*dkp = NULL;
 }

 void
--- a/lib/dns/dnstap.c
+++ b/lib/dns/dnstap.c
@ -1334,6 +1334,7 @@ dns_dtdata_free(dns_dtdata_t **dp) {
 	REQUIRE(dp != NULL && *dp != NULL);

 	d = *dp;
+	*dp = NULL;

 	if (d->msg != NULL)
 		dns_message_destroy(&d->msg);
@ -1341,6 +1342,4 @@ dns_dtdata_free(dns_dtdata_t **dp) {
 		dnstap__dnstap__free_unpacked(d->frame, NULL);

 	isc_mem_putanddetach(&d->mctx, d, sizeof(*d));
-
-	*dp = NULL;
 }
--- a/lib/dns/dst_api.c
+++ b/lib/dns/dst_api.c
@ -353,13 +353,13 @@ dst_context_destroy(dst_context_t **dctxp) {
 	REQUIRE(dctxp != NULL && VALID_CTX(*dctxp));

 	dctx = *dctxp;
+	*dctxp = NULL;
 	INSIST(dctx->key->func->destroyctx != NULL);
 	dctx->key->func->destroyctx(dctx);
 	if (dctx->key != NULL)
 		dst_key_free(&dctx->key);
 	dctx->magic = 0;
 	isc_mem_putanddetach(&dctx->mctx, dctx, sizeof(dst_context_t));
-	*dctxp = NULL;
 }

 isc_result_t
--- a/lib/dns/dyndb.c
+++ b/lib/dns/dyndb.c
@ -198,11 +198,10 @@ unload_library(dyndb_implementation_t **impp) {
 	REQUIRE(impp != NULL && *impp != NULL);

 	imp = *impp;
+	*impp = NULL;

 	isc_mem_free(imp->mctx, imp->name);
 	isc_mem_putanddetach(&imp->mctx, imp, sizeof(dyndb_implementation_t));
-
-	*impp = NULL;
 }
 #elif _WIN32
 static isc_result_t
@ -310,11 +309,10 @@ unload_library(dyndb_implementation_t **impp) {
 	REQUIRE(impp != NULL && *impp != NULL);

 	imp = *impp;
+	*impp = NULL;

 	isc_mem_free(imp->mctx, imp->name);
 	isc_mem_putanddetach(&imp->mctx, imp, sizeof(dyndb_implementation_t));
-
-	*impp = NULL;
 }
 #else	/* HAVE_DLFCN_H || _WIN32 */
 static isc_result_t
--- a/lib/dns/forward.c
+++ b/lib/dns/forward.c
@ -201,14 +201,13 @@ dns_fwdtable_destroy(dns_fwdtable_t **fwdtablep) {
 	REQUIRE(fwdtablep != NULL && VALID_FWDTABLE(*fwdtablep));

 	fwdtable = *fwdtablep;
+	*fwdtablep = NULL;

 	dns_rbt_destroy(&fwdtable->table);
 	isc_rwlock_destroy(&fwdtable->rwlock);
 	fwdtable->magic = 0;

 	isc_mem_putanddetach(&fwdtable->mctx, fwdtable, sizeof(dns_fwdtable_t));
-
-	*fwdtablep = NULL;
 }

 /***
--- a/lib/dns/journal.c
+++ b/lib/dns/journal.c
@ -1233,6 +1233,7 @@ dns_journal_write_transaction(dns_journal_t *j, dns_diff_t *diff) {
 void
 dns_journal_destroy(dns_journal_t **journalp) {
 	dns_journal_t *j = *journalp;
+	*journalp = NULL;
 	REQUIRE(DNS_JOURNAL_VALID(j));

 	j->it.result = ISC_R_FAILURE;
@ -1254,7 +1255,6 @@ dns_journal_destroy(dns_journal_t **journalp) {
 		(void)isc_stdio_close(j->fp);
 	j->magic = 0;
 	isc_mem_putanddetach(&j->mctx, j, sizeof(*j));
-	*journalp = NULL;
 }

 /*
--- a/lib/dns/lookup.c
+++ b/lib/dns/lookup.c
@ -416,6 +416,7 @@ dns_lookup_destroy(dns_lookup_t **lookupp) {

 	REQUIRE(lookupp != NULL);
 	lookup = *lookupp;
+	*lookupp = NULL;
 	REQUIRE(VALID_LOOKUP(lookup));
 	REQUIRE(lookup->event == NULL);
 	REQUIRE(lookup->task == NULL);
@ -428,6 +429,4 @@ dns_lookup_destroy(dns_lookup_t **lookupp) {
 	isc_mutex_destroy(&lookup->lock);
 	lookup->magic = 0;
 	isc_mem_putanddetach(&lookup->mctx, lookup, sizeof(*lookup));
-
-	*lookupp = NULL;
 }
--- a/lib/dns/master.c
+++ b/lib/dns/master.c
@ -404,9 +404,8 @@ dns_loadctx_detach(dns_loadctx_t **lctxp) {

 	REQUIRE(lctxp != NULL);
 	lctx = *lctxp;
-	REQUIRE(DNS_LCTX_VALID(lctx));
-
 	*lctxp = NULL;
+	REQUIRE(DNS_LCTX_VALID(lctx));

 	if (isc_refcount_decrement(&lctx->references) == 1) {
 		loadctx_destroy(lctx);
--- a/lib/dns/masterdump.c
+++ b/lib/dns/masterdump.c
@ -1317,9 +1317,8 @@ dns_dumpctx_detach(dns_dumpctx_t **dctxp) {

 	REQUIRE(dctxp != NULL);
 	dctx = *dctxp;
-	REQUIRE(DNS_DCTX_VALID(dctx));
-
 	*dctxp = NULL;
+	REQUIRE(DNS_DCTX_VALID(dctx));

 	if (isc_refcount_decrement(&dctx->references) == 1) {
 		dumpctx_destroy(dctx);
--- a/lib/dns/message.c
+++ b/lib/dns/message.c
@ -2555,10 +2555,10 @@ dns_message_puttempname(dns_message_t *msg, dns_name_t **itemp) {
 	REQUIRE(DNS_MESSAGE_VALID(msg));
 	REQUIRE(itemp != NULL && *itemp != NULL);
 	item = *itemp;
+	*itemp = NULL;
 	REQUIRE(!ISC_LINK_LINKED(item, link));
 	REQUIRE(ISC_LIST_HEAD(item->list) == NULL);

-	*itemp = NULL;
 	if (dns_name_dynamic(item))
 		dns_name_free(item, msg->mctx);
 	isc_mempool_put(msg->namepool, item);
--- a/lib/dns/peer.c
+++ b/lib/dns/peer.c
@ -106,6 +106,7 @@ peerlist_delete(dns_peerlist_t **list) {
 	REQUIRE(DNS_PEERLIST_VALID(*list));

 	l = *list;
+	*list = NULL;

 	isc_refcount_destroy(&l->refs);

@ -119,8 +120,6 @@ peerlist_delete(dns_peerlist_t **list) {

 	l->magic = 0;
 	isc_mem_put(l->mem, l, sizeof(*l));
-
-	*list = NULL;
 }

 void
@ -270,6 +269,7 @@ peer_delete(dns_peer_t **peer) {
 	REQUIRE(DNS_PEER_VALID(*peer));

 	p = *peer;
+	*peer = NULL;

 	isc_refcount_destroy(&p->refs);

@ -293,8 +293,6 @@ peer_delete(dns_peer_t **peer) {
 			    sizeof(*p->transfer_source));

 	isc_mem_put(mem, p, sizeof(*p));
-
-	*peer = NULL;
 }

 isc_result_t
--- a/lib/dns/rbt.c
+++ b/lib/dns/rbt.c
@ -1000,6 +1000,8 @@ dns_rbt_destroy2(dns_rbt_t **rbtp, unsigned int quantum) {
 	if (rbt->root != NULL)
 		return (ISC_R_QUOTA);

+	*rbtp = NULL;
+
 	INSIST(rbt->nodecount == 0);

 	rbt->mmap_location = NULL;
@ -1011,7 +1013,6 @@ dns_rbt_destroy2(dns_rbt_t **rbtp, unsigned int quantum) {
 	rbt->magic = 0;

 	isc_mem_putanddetach(&rbt->mctx, rbt, sizeof(*rbt));
-	*rbtp = NULL;
 	return (ISC_R_SUCCESS);
 }

@ -2768,11 +2769,11 @@ deletefromlevel(dns_rbtnode_t *item, dns_rbtnode_t **rootp) {
 static void
 freenode(dns_rbt_t *rbt, dns_rbtnode_t **nodep) {
 	dns_rbtnode_t *node = *nodep;
+	*nodep = NULL;

 	if (node->is_mmapped == 0) {
 		isc_mem_put(rbt->mctx, node, NODE_SIZE(node));
 	}
-	*nodep = NULL;

 	rbt->nodecount--;
 }
--- a/lib/dns/request.c
+++ b/lib/dns/request.c
@ -283,9 +283,9 @@ requestmgr_detach(dns_requestmgr_t **requestmgrp) {

 	REQUIRE(requestmgrp != NULL);
 	requestmgr = *requestmgrp;
+	*requestmgrp = NULL;
 	REQUIRE(VALID_REQUESTMGR(requestmgr));

-	*requestmgrp = NULL;
 	LOCK(&requestmgr->lock);
 	INSIST(requestmgr->iref > 0);
 	requestmgr->iref--;
@ -328,6 +328,7 @@ dns_requestmgr_detach(dns_requestmgr_t **requestmgrp) {

 	REQUIRE(requestmgrp != NULL);
 	requestmgr = *requestmgrp;
+	*requestmgrp = NULL;
 	REQUIRE(VALID_REQUESTMGR(requestmgr));

 	LOCK(&requestmgr->lock);
@ -346,8 +347,6 @@ dns_requestmgr_detach(dns_requestmgr_t **requestmgrp) {

 	if (need_destroy)
 		mgr_destroy(requestmgr);
-
-	*requestmgrp = NULL;
 }

 static void
@ -1202,6 +1201,7 @@ dns_request_destroy(dns_request_t **requestp) {
 	REQUIRE(requestp != NULL && VALID_REQUEST(*requestp));

 	request = *requestp;
+	*requestp = NULL;

 	req_log(ISC_LOG_DEBUG(3), "dns_request_destroy: request %p", request);

@ -1223,8 +1223,6 @@ dns_request_destroy(dns_request_t **requestp) {
 	INSIST(request->timer == NULL);

 	req_destroy(request);
-
-	*requestp = NULL;
 }

 /***
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@ -1129,6 +1129,7 @@ resquery_destroy(resquery_t **queryp) {

 	REQUIRE(queryp != NULL);
 	query = *queryp;
+	*queryp = NULL;
 	REQUIRE(!ISC_LINK_LINKED(query, link));

 	INSIST(query->tcpsocket == NULL);
@ -1144,7 +1145,6 @@ resquery_destroy(resquery_t **queryp) {

 	query->magic = 0;
 	isc_mem_put(query->mctx, query, sizeof(*query));
-	*queryp = NULL;

 	if (empty)
 		empty_bucket(res);
@ -10339,12 +10339,11 @@ dns_resolver_detach(dns_resolver_t **resp) {

 	REQUIRE(resp != NULL);
 	res = *resp;
+	*resp = NULL;
 	REQUIRE(VALID_RESOLVER(res));

 	RTRACE("detach");

-	*resp = NULL;
-
 	if (isc_refcount_decrement(&res->references) == 1) {
 		LOCK(&res->lock);
 		INSIST(atomic_load_acquire(&res->exiting));
@ -10684,6 +10683,7 @@ dns_resolver_destroyfetch(dns_fetch_t **fetchp) {

 	REQUIRE(fetchp != NULL);
 	fetch = *fetchp;
+	*fetchp = NULL;
 	REQUIRE(DNS_FETCH_VALID(fetch));
 	fctx = fetch->private;
 	REQUIRE(VALID_FCTX(fctx));
@ -10712,7 +10712,6 @@ dns_resolver_destroyfetch(dns_fetch_t **fetchp) {
 	UNLOCK(&res->buckets[bucketnum].lock);

 	isc_mem_putanddetach(&fetch->mctx, fetch, sizeof(*fetch));
-	*fetchp = NULL;

 	if (bucket_empty)
 		empty_bucket(res);
--- a/lib/dns/sdb.c
+++ b/lib/dns/sdb.c
@ -247,12 +247,11 @@ dns_sdb_unregister(dns_sdbimplementation_t **sdbimp) {
 	REQUIRE(sdbimp != NULL && *sdbimp != NULL);

 	imp = *sdbimp;
+	*sdbimp = NULL;
 	dns_db_unregister(&imp->dbimp);
 	isc_mutex_destroy(&imp->driverlock);

 	isc_mem_putanddetach(&imp->mctx, imp, sizeof(dns_sdbimplementation_t));
-
-	*sdbimp = NULL;
 }

 static inline unsigned int
--- a/lib/dns/sdlz.c
+++ b/lib/dns/sdlz.c
@ -2068,6 +2068,7 @@ dns_sdlzunregister(dns_sdlzimplementation_t **sdlzimp) {
 	REQUIRE(sdlzimp != NULL && *sdlzimp != NULL);

 	imp = *sdlzimp;
+	*sdlzimp = NULL;

 	/* Unregister the DLZ driver implementation */
 	dns_dlzunregister(&imp->dlz_imp);
@ -2080,8 +2081,6 @@ dns_sdlzunregister(dns_sdlzimplementation_t **sdlzimp) {
 	 * remove it from the memory context.
 	 */
 	isc_mem_putanddetach(&imp->mctx, imp, sizeof(dns_sdlzimplementation_t));
-
-	*sdlzimp = NULL;
 }


--- a/lib/dns/ssu.c
+++ b/lib/dns/ssu.c
@ -119,8 +119,8 @@ dns_ssutable_detach(dns_ssutable_t **tablep) {

 	REQUIRE(tablep != NULL);
 	table = *tablep;
-	REQUIRE(VALID_SSUTABLE(table));
 	*tablep = NULL;
+	REQUIRE(VALID_SSUTABLE(table));

 	if (isc_refcount_decrement(&table->references) == 1) {
 		destroy(table);
--- a/lib/dns/tkey.c
+++ b/lib/dns/tkey.c
@ -131,6 +131,7 @@ dns_tkeyctx_destroy(dns_tkeyctx_t **tctxp) {
 	REQUIRE(tctxp != NULL && *tctxp != NULL);

 	tctx = *tctxp;
+	*tctxp = NULL;
 	mctx = tctx->mctx;

 	if (tctx->dhkey != NULL)
@ -146,7 +147,6 @@ dns_tkeyctx_destroy(dns_tkeyctx_t **tctxp) {
 	if (tctx->gsscred != NULL)
 		dst_gssapi_releasecred(&tctx->gsscred);
 	isc_mem_putanddetach(&mctx, tctx, sizeof(dns_tkeyctx_t));
-	*tctxp = NULL;
 }

 static isc_result_t
--- a/lib/dns/tsec.c
+++ b/lib/dns/tsec.c
@ -109,6 +109,7 @@ dns_tsec_destroy(dns_tsec_t **tsecp) {

 	REQUIRE(tsecp != NULL && *tsecp != NULL);
 	tsec = *tsecp;
+	*tsecp = NULL;
 	REQUIRE(DNS_TSEC_VALID(tsec));

 	switch (tsec->type) {
@ -125,8 +126,6 @@ dns_tsec_destroy(dns_tsec_t **tsecp) {

 	tsec->magic = 0;
 	isc_mem_put(tsec->mctx, tsec, sizeof(*tsec));
-
-	*tsecp = NULL;
 }

 dns_tsectype_t
--- a/lib/dns/validator.c
+++ b/lib/dns/validator.c
@ -3307,6 +3307,7 @@ dns_validator_destroy(dns_validator_t **validatorp) {

 	REQUIRE(validatorp != NULL);
 	val = *validatorp;
+	*validatorp = NULL;
 	REQUIRE(VALID_VALIDATOR(val));

 	LOCK(&val->lock);
@ -3319,8 +3320,6 @@ dns_validator_destroy(dns_validator_t **validatorp) {
 	if (want_destroy) {
 		destroy(val);
 	}
-
-	*validatorp = NULL;
 }

 static void
--- a/lib/dns/view.c
+++ b/lib/dns/view.c
@ -667,8 +667,8 @@ dns_view_weakdetach(dns_view_t **viewp) {

 	REQUIRE(viewp != NULL);
 	view = *viewp;
-	REQUIRE(DNS_VIEW_VALID(view));
 	*viewp = NULL;
+	REQUIRE(DNS_VIEW_VALID(view));

 	if (isc_refcount_decrement(&view->weakrefs) == 1) {
 		destroy(view);
--- a/lib/dns/xfrin.c
+++ b/lib/dns/xfrin.c
@ -701,10 +701,10 @@ dns_xfrin_attach(dns_xfrin_ctx_t *source, dns_xfrin_ctx_t **target) {
 void
 dns_xfrin_detach(dns_xfrin_ctx_t **xfrp) {
 	dns_xfrin_ctx_t *xfr = *xfrp;
+	*xfrp = NULL;
 	INSIST(xfr->refcount > 0);
 	xfr->refcount--;
 	maybe_free(xfr);
-	*xfrp = NULL;
 }

 static void
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@ -16987,13 +16987,12 @@ dns_zonemgr_detach(dns_zonemgr_t **zmgrp) {

 	REQUIRE(zmgrp != NULL);
 	zmgr = *zmgrp;
+	*zmgrp = NULL;
 	REQUIRE(DNS_ZONEMGR_VALID(zmgr));

 	if (isc_refcount_decrement(&zmgr->refs) == 1) {
 		zonemgr_free(zmgr);
 	}
-
-	*zmgrp = NULL;
 }

 isc_result_t
@ -17429,9 +17428,8 @@ zonemgr_putio(dns_io_t **iop) {

 	REQUIRE(iop != NULL);
 	io = *iop;
-	REQUIRE(DNS_IO_VALID(io));
-
 	*iop = NULL;
+	REQUIRE(DNS_IO_VALID(io));

 	INSIST(!ISC_LINK_LINKED(io, link));
 	INSIST(io->event == NULL);
--- a/lib/irs/dnsconf.c
+++ b/lib/irs/dnsconf.c
@ -275,6 +275,7 @@ irs_dnsconf_destroy(irs_dnsconf_t **confp) {

 	REQUIRE(confp != NULL);
 	conf = *confp;
+	*confp = NULL;
 	REQUIRE(IRS_DNSCONF_VALID(conf));

 	while ((keyent = ISC_LIST_HEAD(conf->trusted_keylist)) != NULL) {
@ -287,8 +288,6 @@ irs_dnsconf_destroy(irs_dnsconf_t **confp) {
 	}

 	isc_mem_put(conf->mctx, conf, sizeof(*conf));
-
-	*confp = NULL;
 }

 irs_dnsconf_dnskeylist_t *
--- a/lib/irs/resconf.c
+++ b/lib/irs/resconf.c
@ -605,6 +605,7 @@ irs_resconf_destroy(irs_resconf_t **confp) {

 	REQUIRE(confp != NULL);
 	conf = *confp;
+	*confp = NULL;
 	REQUIRE(IRS_RESCONF_VALID(conf));

 	while ((searchentry = ISC_LIST_HEAD(conf->searchlist)) != NULL) {
@ -626,8 +627,6 @@ irs_resconf_destroy(irs_resconf_t **confp) {
 	}

 	isc_mem_put(conf->mctx, conf, sizeof(*conf));
-
-	*confp = NULL;
 }

 isc_sockaddrlist_t *
--- a/lib/isc/buffer.c
+++ b/lib/isc/buffer.c
@ -609,7 +609,7 @@ isc_buffer_free(isc_buffer_t **dynbuffer) {
 	REQUIRE((*dynbuffer)->mctx != NULL);

 	dbuf = *dynbuffer;
-	*dynbuffer = NULL;	/* destroy external reference */
+	*dynbuffer = NULL;/* destroy external reference */
 	mctx = dbuf->mctx;
 	dbuf->mctx = NULL;

--- a/lib/isc/counter.c
+++ b/lib/isc/counter.c
@ -101,9 +101,8 @@ isc_counter_detach(isc_counter_t **counterp) {

 	REQUIRE(counterp != NULL && *counterp != NULL);
 	counter = *counterp;
-	REQUIRE(VALID_COUNTER(counter));
-
 	*counterp = NULL;
+	REQUIRE(VALID_COUNTER(counter));

 	if (isc_refcount_decrement(&counter->references) == 1) {
 		destroy(counter);
--- a/lib/isc/event.c
+++ b/lib/isc/event.c
@ -84,6 +84,7 @@ isc_event_free(isc_event_t **eventp) {

 	REQUIRE(eventp != NULL);
 	event = *eventp;
+	*eventp = NULL;
 	REQUIRE(event != NULL);

 	REQUIRE(!ISC_LINK_LINKED(event, ev_link));
@ -91,6 +92,4 @@ isc_event_free(isc_event_t **eventp) {

 	if (event->ev_destroy != NULL)
 		(event->ev_destroy)(event);
-
-	*eventp = NULL;
 }
--- a/lib/isc/heap.c
+++ b/lib/isc/heap.c
@ -112,6 +112,7 @@ isc_heap_destroy(isc_heap_t **heapp) {

 	REQUIRE(heapp != NULL);
 	heap = *heapp;
+	*heapp = NULL;
 	REQUIRE(VALID_HEAP(heap));

 	if (heap->array != NULL)
@ -119,8 +120,6 @@ isc_heap_destroy(isc_heap_t **heapp) {
 			    heap->size * sizeof(void *));
 	heap->magic = 0;
 	isc_mem_putanddetach(&heap->mctx, heap, sizeof(*heap));
-
-	*heapp = NULL;
 }

 static bool
--- a/lib/isc/ht.c
+++ b/lib/isc/ht.c
@ -228,10 +228,9 @@ isc_ht_iter_destroy(isc_ht_iter_t **itp) {
 	REQUIRE(itp != NULL && *itp != NULL);

 	it = *itp;
+	*itp = NULL;
 	ht = it->ht;
 	isc_mem_put(ht->mctx, it, sizeof(isc_ht_iter_t));
-
-	*itp = NULL;
 }

 isc_result_t
--- a/lib/isc/lex.c
+++ b/lib/isc/lex.c
@ -119,6 +119,7 @@ isc_lex_destroy(isc_lex_t **lexp) {

 	REQUIRE(lexp != NULL);
 	lex = *lexp;
+	*lexp = NULL;
 	REQUIRE(VALID_LEX(lex));

 	while (!EMPTY(lex->sources))
@ -127,8 +128,6 @@ isc_lex_destroy(isc_lex_t **lexp) {
 		isc_mem_put(lex->mctx, lex->data, lex->max_token + 1);
 	lex->magic = 0;
 	isc_mem_put(lex->mctx, lex, sizeof(*lex));
-
-	*lexp = NULL;
 }

 unsigned int
--- a/lib/isc/log.c
+++ b/lib/isc/log.c
@ -431,6 +431,7 @@ isc_log_destroy(isc_log_t **lctxp) {
 	REQUIRE(lctxp != NULL && VALID_CONTEXT(*lctxp));

 	lctx = *lctxp;
+	*lctxp = NULL;
 	mctx = lctx->mctx;

 	if (lctx->logconfig != NULL) {
@ -458,8 +459,6 @@ isc_log_destroy(isc_log_t **lctxp) {
 	lctx->magic = 0;

 	isc_mem_putanddetach(&mctx, lctx, sizeof(*lctx));
-
-	*lctxp = NULL;
 }

 void
@ -474,6 +473,7 @@ isc_logconfig_destroy(isc_logconfig_t **lcfgp) {
 	REQUIRE(lcfgp != NULL && VALID_CONFIG(*lcfgp));

 	lcfg = *lcfgp;
+	*lcfgp = NULL;

 	/*
 	 * This function cannot be called with a logconfig that is in
@ -524,8 +524,6 @@ isc_logconfig_destroy(isc_logconfig_t **lcfgp) {
 	lcfg->magic = 0;

 	isc_mem_put(mctx, lcfg, sizeof(*lcfg));
-
-	*lcfgp = NULL;
 }

 void
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@ -237,6 +237,7 @@ nm_destroy(isc_nm_t **mgr0) {
 	REQUIRE(!isc__nm_in_netthread());

 	isc_nm_t *mgr = *mgr0;
+	*mgr0 = NULL;

 	isc_refcount_destroy(&mgr->references);

@ -300,7 +301,6 @@ nm_destroy(isc_nm_t **mgr0) {
 	isc_mem_put(mgr->mctx, mgr->workers,
 		    mgr->nworkers * sizeof(isc__networker_t));
 	isc_mem_putanddetach(&mgr->mctx, mgr, sizeof(*mgr));
-	*mgr0 = NULL;
 }

 void
--- a/lib/isc/pool.c
+++ b/lib/isc/pool.c
@ -110,6 +110,7 @@ isc_pool_expand(isc_pool_t **sourcep, unsigned int count,
 	REQUIRE(targetp != NULL && *targetp == NULL);

 	pool = *sourcep;
+	*sourcep = NULL;
 	if (count > pool->count) {
 		isc_pool_t *newpool = NULL;
 		unsigned int i;
@ -143,7 +144,6 @@ isc_pool_expand(isc_pool_t **sourcep, unsigned int count,
 		pool = newpool;
 	}

-	*sourcep = NULL;
 	*targetp = pool;
 	return (ISC_R_SUCCESS);
 }
@ -152,11 +152,11 @@ void
 isc_pool_destroy(isc_pool_t **poolp) {
 	unsigned int i;
 	isc_pool_t *pool = *poolp;
+	*poolp = NULL;
 	for (i = 0; i < pool->count; i++) {
 		if (pool->free != NULL && pool->pool[i] != NULL)
 			pool->free(&pool->pool[i]);
 	}
 	isc_mem_put(pool->mctx, pool->pool, pool->count * sizeof(void *));
 	isc_mem_putanddetach(&pool->mctx, pool, sizeof(*pool));
-	*poolp = NULL;
 }
--- a/lib/isc/ratelimiter.c
+++ b/lib/isc/ratelimiter.c
@ -296,12 +296,11 @@ isc_ratelimiter_detach(isc_ratelimiter_t **rlp) {
 	REQUIRE(rlp != NULL && *rlp != NULL);

 	rl = *rlp;
+	*rlp = NULL;

 	if (isc_refcount_decrement(&rl->references) == 1) {
 		ratelimiter_free(rl);
 	}
-
-	*rlp = NULL;
 }

 isc_result_t
--- a/lib/isc/symtab.c
+++ b/lib/isc/symtab.c
@ -88,6 +88,7 @@ isc_symtab_destroy(isc_symtab_t **symtabp) {

 	REQUIRE(symtabp != NULL);
 	symtab = *symtabp;
+	*symtabp = NULL;
 	REQUIRE(VALID_SYMTAB(symtab));

 	for (i = 0; i < symtab->size; i++) {
@ -105,8 +106,6 @@ isc_symtab_destroy(isc_symtab_t **symtabp) {
 		    symtab->size * sizeof(eltlist_t));
 	symtab->magic = 0;
 	isc_mem_putanddetach(&symtab->mctx, symtab, sizeof(*symtab));
-
-	*symtabp = NULL;
 }

 static inline unsigned int
--- a/lib/isc/task.c
+++ b/lib/isc/task.c
@ -492,6 +492,7 @@ task_send(isc__task_t *task, isc_event_t **eventp, int c) {

 	REQUIRE(eventp != NULL);
 	event = *eventp;
+	*eventp = NULL;
 	REQUIRE(event != NULL);
 	REQUIRE(event->ev_type > 0);
 	REQUIRE(task->state != task_state_done);
@ -511,7 +512,6 @@ task_send(isc__task_t *task, isc_event_t **eventp, int c) {
 	       task->state == task_state_pausing);
 	ENQUEUE(task->events, event, ev_link);
 	task->nevents++;
-	*eventp = NULL;

 	return (was_idle);
 }
--- a/lib/isc/taskpool.c
+++ b/lib/isc/taskpool.c
@ -35,7 +35,7 @@ struct isc_taskpool {
 *** Functions.
 ***/

-static isc_result_t
+static void
 alloc_pool(isc_taskmgr_t *tmgr, isc_mem_t *mctx, unsigned int ntasks,
 	   unsigned int quantum, isc_taskpool_t **poolp)
 {
@ -50,11 +50,11 @@ alloc_pool(isc_taskmgr_t *tmgr, isc_mem_t *mctx, unsigned int ntasks,
 	pool->quantum = quantum;
 	pool->tmgr = tmgr;
 	pool->tasks = isc_mem_get(mctx, ntasks * sizeof(isc_task_t *));
-	for (i = 0; i < ntasks; i++)
+	for (i = 0; i < ntasks; i++) {
 		pool->tasks[i] = NULL;
+	}

 	*poolp = pool;
-	return (ISC_R_SUCCESS);
 }

 isc_result_t
@ -69,9 +69,7 @@ isc_taskpool_create(isc_taskmgr_t *tmgr, isc_mem_t *mctx,
 	INSIST(ntasks > 0);

 	/* Allocate the pool structure */
-	result = alloc_pool(tmgr, mctx, ntasks, quantum, &pool);
-	if (result != ISC_R_SUCCESS)
-		return (result);
+	alloc_pool(tmgr, mctx, ntasks, quantum, &pool);

 	/* Create the tasks */
 	for (i = 0; i < ntasks; i++) {
@ -109,15 +107,14 @@ isc_taskpool_expand(isc_taskpool_t **sourcep, unsigned int size,
 	REQUIRE(targetp != NULL && *targetp == NULL);

 	pool = *sourcep;
+	*sourcep = NULL;
 	if (size > pool->ntasks) {
 		isc_taskpool_t *newpool = NULL;
 		unsigned int i;

 		/* Allocate a new pool structure */
-		result = alloc_pool(pool->tmgr, pool->mctx, size,
-				    pool->quantum, &newpool);
-		if (result != ISC_R_SUCCESS)
-			return (result);
+		alloc_pool(pool->tmgr, pool->mctx, size,
+			   pool->quantum, &newpool);

 		/* Copy over the tasks from the old pool */
 		for (i = 0; i < pool->ntasks; i++) {
@ -130,6 +127,7 @@ isc_taskpool_expand(isc_taskpool_t **sourcep, unsigned int size,
 			result = isc_task_create(pool->tmgr, pool->quantum,
 						 &newpool->tasks[i]);
 			if (result != ISC_R_SUCCESS) {
+				*sourcep = pool;
 				isc_taskpool_destroy(&newpool);
 				return (result);
 			}
@ -140,7 +138,6 @@ isc_taskpool_expand(isc_taskpool_t **sourcep, unsigned int size,
 		pool = newpool;
 	}

-	*sourcep = NULL;
 	*targetp = pool;
 	return (ISC_R_SUCCESS);
 }
@ -149,6 +146,7 @@ void
 isc_taskpool_destroy(isc_taskpool_t **poolp) {
 	unsigned int i;
 	isc_taskpool_t *pool = *poolp;
+	*poolp = NULL;
 	for (i = 0; i < pool->ntasks; i++) {
 		if (pool->tasks[i] != NULL)
 			isc_task_detach(&pool->tasks[i]);
@ -156,7 +154,6 @@ isc_taskpool_destroy(isc_taskpool_t **poolp) {
 	isc_mem_put(pool->mctx, pool->tasks,
 		    pool->ntasks * sizeof(isc_task_t *));
 	isc_mem_putanddetach(&pool->mctx, pool, sizeof(*pool));
-	*poolp = NULL;
 }

 void
--- a/lib/isc/unix/interfaceiter.c
+++ b/lib/isc/unix/interfaceiter.c
@ -282,6 +282,7 @@ isc_interfaceiter_destroy(isc_interfaceiter_t **iterp)
 	isc_interfaceiter_t *iter;
 	REQUIRE(iterp != NULL);
 	iter = *iterp;
+	*iterp = NULL;
 	REQUIRE(VALID_IFITER(iter));

 	internal_destroy(iter);
@ -290,5 +291,4 @@ isc_interfaceiter_destroy(isc_interfaceiter_t **iterp)

 	iter->magic = 0;
 	isc_mem_put(iter->mctx, iter, sizeof(*iter));
-	*iterp = NULL;
 }
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@ -1931,6 +1931,7 @@ allocate_socket(isc__socketmgr_t *manager, isc_sockettype_t type,
 static void
 free_socket(isc__socket_t **socketp) {
 	isc__socket_t *sock = *socketp;
+	*socketp = NULL;

 	INSIST(VALID_SOCKET(sock));
 	isc_refcount_destroy(&sock->references);
@ -1949,8 +1950,6 @@ free_socket(isc__socket_t **socketp) {
 	isc_mutex_destroy(&sock->lock);

 	isc_mem_put(sock->manager->mctx, sock, sizeof(*sock));
-
-	*socketp = NULL;
 }

 #ifdef SO_RCVBUF
--- a/lib/isc/win32/interfaceiter.c
+++ b/lib/isc/win32/interfaceiter.c
@ -516,6 +516,7 @@ isc_interfaceiter_destroy(isc_interfaceiter_t **iterp) {
 	isc_interfaceiter_t *iter;
 	REQUIRE(iterp != NULL);
 	iter = *iterp;
+	*iterp = NULL;
 	REQUIRE(VALID_IFITER(iter));

 	if (iter->buf4 != NULL)
@ -525,5 +526,4 @@ isc_interfaceiter_destroy(isc_interfaceiter_t **iterp) {

 	iter->magic = 0;
 	isc_mem_put(iter->mctx, iter, sizeof(*iter));
-	*iterp = NULL;
 }
--- a/lib/isc/win32/socket.c
+++ b/lib/isc/win32/socket.c
@ -1752,6 +1752,7 @@ isc_socket_detach(isc_socket_t **socketp) {

 	REQUIRE(socketp != NULL);
 	sock = *socketp;
+	*socketp = NULL;
 	REQUIRE(VALID_SOCKET(sock));

 	LOCK(&sock->lock);
@ -1771,8 +1772,6 @@ isc_socket_detach(isc_socket_t **socketp) {
 	}

 	maybe_free_socket(&sock, __LINE__); /* Also unlocks the socket lock */
-
-	*socketp = NULL;
 }

 isc_result_t
@ -2565,6 +2564,7 @@ isc_socketmgr_destroy(isc_socketmgr_t **managerp) {

 	REQUIRE(managerp != NULL);
 	manager = *managerp;
+	*managerp = NULL;
 	REQUIRE(VALID_MANAGER(manager));

 	LOCK(&manager->lock);
@ -2606,8 +2606,6 @@ isc_socketmgr_destroy(isc_socketmgr_t **managerp) {
 	}
 	manager->magic = 0;
 	isc_mem_putanddetach(&manager->mctx, manager, sizeof(*manager));
-
-	*managerp = NULL;
 }

 static void
--- a/lib/isccc/sexpr.c
+++ b/lib/isccc/sexpr.c
@ -115,6 +115,7 @@ isccc_sexpr_free(isccc_sexpr_t **sexprp) {
 	isccc_sexpr_t *item;

 	sexpr = *sexprp;
+	*sexprp = NULL;
 	if (sexpr == NULL)
 		return;
 	switch (sexpr->type) {
@ -134,8 +135,6 @@ isccc_sexpr_free(isccc_sexpr_t **sexprp) {
 		break;
 	}
 	free(sexpr);
-
-	*sexprp = NULL;
 }

 static bool
--- a/lib/isccc/symtab.c
+++ b/lib/isccc/symtab.c
@ -110,6 +110,7 @@ isccc_symtab_destroy(isccc_symtab_t **symtabp) {

 	REQUIRE(symtabp != NULL);
 	symtab = *symtabp;
+	*symtabp = NULL;
 	REQUIRE(VALID_SYMTAB(symtab));

 	for (i = 0; i < symtab->size; i++) {
@ -123,8 +124,6 @@ isccc_symtab_destroy(isccc_symtab_t **symtabp) {
 	free(symtab->table);
 	symtab->magic = 0;
 	free(symtab);
-
-	*symtabp = NULL;
 }

 static inline unsigned int
--- a/lib/ns/client.c
+++ b/lib/ns/client.c
@ -2382,17 +2382,17 @@ clientmgr_attach(ns_clientmgr_t *source, ns_clientmgr_t **targetp) {

 static void
 clientmgr_detach(ns_clientmgr_t **mp) {
+	int32_t oldrefs;
 	ns_clientmgr_t *mgr = *mp;
-	int32_t oldrefs = isc_refcount_decrement(&mgr->references);
+	*mp = NULL;

+	oldrefs = isc_refcount_decrement(&mgr->references);
 	isc_log_write(ns_lctx, NS_LOGCATEGORY_CLIENT,
 		      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(3),
 		      "clientmgr @%p detach: %d", mgr, oldrefs - 1);
 	if (oldrefs == 1) {
 		clientmgr_destroy(mgr);
 	}
-
-	*mp = NULL;
 }

 static void
@ -2506,6 +2506,7 @@ ns_clientmgr_destroy(ns_clientmgr_t **managerp) {

 	REQUIRE(managerp != NULL);
 	manager = *managerp;
+	*managerp = NULL;
 	REQUIRE(VALID_MANAGER(manager));

 	MTRACE("destroy");
@ -2529,8 +2530,6 @@ ns_clientmgr_destroy(ns_clientmgr_t **managerp) {
 	if (isc_refcount_decrement(&manager->references) == 1) {
 		clientmgr_destroy(manager);
 	}
-
-	*managerp = NULL;
 }

 isc_sockaddr_t *
--- a/lib/ns/interfacemgr.c
+++ b/lib/ns/interfacemgr.c
@ -347,12 +347,12 @@ ns_interfacemgr_attach(ns_interfacemgr_t *source, ns_interfacemgr_t **target) {
 void
 ns_interfacemgr_detach(ns_interfacemgr_t **targetp) {
 	ns_interfacemgr_t *target = *targetp;
+	*targetp = NULL;
 	REQUIRE(target != NULL);
 	REQUIRE(NS_INTERFACEMGR_VALID(target));
 	if (isc_refcount_decrement(&target->references) == 1) {
 		ns_interfacemgr_destroy(target);
 	}
-	*targetp = NULL;
 }

 void
@ -607,12 +607,12 @@ ns_interface_attach(ns_interface_t *source, ns_interface_t **target) {
 void
 ns_interface_detach(ns_interface_t **targetp) {
 	ns_interface_t *target = *targetp;
+	*targetp = NULL;
 	REQUIRE(target != NULL);
 	REQUIRE(NS_INTERFACE_VALID(target));
 	if (isc_refcount_decrement(&target->references) == 1) {
 		ns_interface_destroy(target);
 	}
-	*targetp = NULL;
 }

 /*%
--- a/lib/ns/listenlist.c
+++ b/lib/ns/listenlist.c
@ -81,11 +81,11 @@ ns_listenlist_attach(ns_listenlist_t *source, ns_listenlist_t **target) {
 void
 ns_listenlist_detach(ns_listenlist_t **listp) {
 	ns_listenlist_t *list = *listp;
+	*listp = NULL;
 	INSIST(list->refcount > 0);
 	list->refcount--;
 	if (list->refcount == 0)
 		destroy(list);
-	*listp = NULL;
 }

 isc_result_t
--- a/lib/ns/tests/nstest.c
+++ b/lib/ns/tests/nstest.c
@ -841,6 +841,7 @@ ns_test_qctx_destroy(query_ctx_t **qctxp) {
 	REQUIRE(*qctxp != NULL);

 	qctx = *qctxp;
+	*qctxp = NULL;

 	if (qctx->zone != NULL) {
 		dns_zone_detach(&qctx->zone);
@ -853,7 +854,6 @@ ns_test_qctx_destroy(query_ctx_t **qctxp) {
 	}

 	isc_mem_put(mctx, qctx, sizeof(*qctx));
-	*qctxp = NULL;
 }

 ns_hookresult_t
--- a/lib/ns/xfrout.c
+++ b/lib/ns/xfrout.c
@ -558,8 +558,8 @@ compound_rrstream_create(isc_mem_t *mctx, rrstream_t **soa_stream,
 	s->state = -1;
 	s->result = ISC_R_FAILURE;

-	*soa_stream = NULL;
 	*data_stream = NULL;
+	*soa_stream = NULL;
 	*sp = (rrstream_t *) s;
 	return (ISC_R_SUCCESS);
 }
@ -1605,6 +1605,7 @@ sendstream(xfrout_ctx_t *xfr) {
 static void
 xfrout_ctx_destroy(xfrout_ctx_t **xfrp) {
 	xfrout_ctx_t *xfr = *xfrp;
+	*xfrp = NULL;

 	INSIST(xfr->sends == 0);

@ -1629,8 +1630,6 @@ xfrout_ctx_destroy(xfrout_ctx_t **xfrp) {
 		dns_db_detach(&xfr->db);

 	isc_mem_putanddetach(&xfr->mctx, xfr, sizeof(*xfr));
-
-	*xfrp = NULL;
 }

 static void