From: Ondřej Surý <ondrej@isc.org>
Date: Sat, 8 Feb 2020 12:37:54 +0000 (-0800)
Subject: Clear the pointer to destroyed object early using the semantic patch
X-Git-Tag: v9.16.0~12^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bc1d4c9cb44432e24d2db5c762eda64ae9b9a93e;p=thirdparty%2Fbind9.git

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.
---

diff --git a/bin/dnssec/dnssec-cds.c b/bin/dnssec/dnssec-cds.c
index 283e754cdc3..57c34d9e63c 100644
--- 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;
 }
 
 /*
diff --git a/bin/named/controlconf.c b/bin/named/controlconf.c
index f07590652a1..41fd61a4eef 100644
--- 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;
 }
diff --git a/bin/nsupdate/nsupdate.c b/bin/nsupdate/nsupdate.c
index c431ebe39fb..687fc3b0f00 100644
--- 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);
 }
 
diff --git a/bin/tests/system/dyndb/driver/instance.c b/bin/tests/system/dyndb/driver/instance.c
index 5650f3ba2ef..962df342e2c 100644
--- 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;
 }
diff --git a/cocci/null-the-pointer-early.spatch b/cocci/null-the-pointer-early.disabled
similarity index 100%
rename from cocci/null-the-pointer-early.spatch
rename to cocci/null-the-pointer-early.disabled
diff --git a/lib/dns/adb.c b/lib/dns/adb.c
index d7f25494dbd..d6b7658db37 100644
--- 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;
diff --git a/lib/dns/badcache.c b/lib/dns/badcache.c
index 389981f8498..a2e76f21860 100644
--- 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
diff --git a/lib/dns/byaddr.c b/lib/dns/byaddr.c
index 5d8dfbf7b85..a1e83bda4d5 100644
--- 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;
 }
diff --git a/lib/dns/cache.c b/lib/dns/cache.c
index f20c1de8a64..75ac923f7cb 100644
--- 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;
diff --git a/lib/dns/catz.c b/lib/dns/catz.c
index e175badff2c..1c63cac051a 100644
--- 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;
diff --git a/lib/dns/client.c b/lib/dns/client.c
index ad4342be6a9..03c2680bcd7 100644
--- 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
diff --git a/lib/dns/dbtable.c b/lib/dns/dbtable.c
index db134e44e83..e018fa7e52f 100644
--- 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);
diff --git a/lib/dns/diff.c b/lib/dns/diff.c
index 3f5d8d2ef64..7789331f909 100644
--- 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
diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index d1b31891383..2c943eeac41 100644
--- 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
diff --git a/lib/dns/dnsrps.c b/lib/dns/dnsrps.c
index c4f68e15b34..8fd9677e226 100644
--- 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
diff --git a/lib/dns/dnssec.c b/lib/dns/dnssec.c
index 8f6e04af863..368137ab2fa 100644
--- 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
diff --git a/lib/dns/dnstap.c b/lib/dns/dnstap.c
index 1f66035ce65..45ac5a541f6 100644
--- 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;
 }
diff --git a/lib/dns/dst_api.c b/lib/dns/dst_api.c
index c778d59f27f..964d6df3f8c 100644
--- 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
diff --git a/lib/dns/dyndb.c b/lib/dns/dyndb.c
index 5b3c964b813..f00fba1ac07 100644
--- 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
diff --git a/lib/dns/forward.c b/lib/dns/forward.c
index 2ac0b31b95d..c42cf73c385 100644
--- 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;
 }
 
 /***
diff --git a/lib/dns/journal.c b/lib/dns/journal.c
index f64bc66eed9..ce2b28d78ea 100644
--- 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;
 }
 
 /*
diff --git a/lib/dns/lookup.c b/lib/dns/lookup.c
index ad5d77c4d3f..d63169d7756 100644
--- 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;
 }
diff --git a/lib/dns/master.c b/lib/dns/master.c
index e7ccc0e04b2..a4dd901d8d7 100644
--- 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);
diff --git a/lib/dns/masterdump.c b/lib/dns/masterdump.c
index b5adeb532ef..595000d5818 100644
--- 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);
diff --git a/lib/dns/message.c b/lib/dns/message.c
index 767db4ce8a3..41b9251037d 100644
--- 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);
diff --git a/lib/dns/peer.c b/lib/dns/peer.c
index bf1ef07d99d..8b1fefe0452 100644
--- 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
diff --git a/lib/dns/rbt.c b/lib/dns/rbt.c
index 34170ce9ab5..e968048dfe4 100644
--- 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--;
 }
diff --git a/lib/dns/request.c b/lib/dns/request.c
index ab1d553eddc..782075fcf91 100644
--- 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;
 }
 
 /***
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 55273d8e170..87e87928021 100644
--- 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);
diff --git a/lib/dns/sdb.c b/lib/dns/sdb.c
index 031928322fe..3da02d5c29f 100644
--- 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
diff --git a/lib/dns/sdlz.c b/lib/dns/sdlz.c
index f163a9b637c..480f9200d4c 100644
--- 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;
 }
 
 
diff --git a/lib/dns/ssu.c b/lib/dns/ssu.c
index 2b17c8362c5..b8177220697 100644
--- 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);
diff --git a/lib/dns/tkey.c b/lib/dns/tkey.c
index 258bce17da2..f28326e356a 100644
--- 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
diff --git a/lib/dns/tsec.c b/lib/dns/tsec.c
index 2b59ac33e7b..cf0055e669b 100644
--- 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
diff --git a/lib/dns/validator.c b/lib/dns/validator.c
index 8fe3aa46f18..4f87c5bc3bb 100644
--- 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
diff --git a/lib/dns/view.c b/lib/dns/view.c
index 38c6634a365..9396763164a 100644
--- 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);
diff --git a/lib/dns/xfrin.c b/lib/dns/xfrin.c
index 3b372570b96..66a231b744b 100644
--- 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
diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index 8604b5f3dc4..d06e3c19d4e 100644
--- 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);
diff --git a/lib/irs/dnsconf.c b/lib/irs/dnsconf.c
index d98c220b26f..b56190ab6e1 100644
--- 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 *
diff --git a/lib/irs/resconf.c b/lib/irs/resconf.c
index 44f340e399c..ff2db506de9 100644
--- 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 *
diff --git a/lib/isc/buffer.c b/lib/isc/buffer.c
index 04b081b025c..2333c7ec3ce 100644
--- 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;
 
diff --git a/lib/isc/counter.c b/lib/isc/counter.c
index 3270e3370a8..96836659202 100644
--- 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);
diff --git a/lib/isc/event.c b/lib/isc/event.c
index 3df4283c88a..938ec9c19ad 100644
--- 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;
 }
diff --git a/lib/isc/heap.c b/lib/isc/heap.c
index 52c08f7cf98..006d087bac2 100644
--- 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
diff --git a/lib/isc/ht.c b/lib/isc/ht.c
index bad7e60fb51..5468eba59ff 100644
--- 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
diff --git a/lib/isc/lex.c b/lib/isc/lex.c
index f8ed95e14fd..e6128c8b585 100644
--- 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
diff --git a/lib/isc/log.c b/lib/isc/log.c
index 1b196052269..c3cdc6abd94 100644
--- 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
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index e900d098256..6f929c6d2c8 100644
--- 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
diff --git a/lib/isc/pool.c b/lib/isc/pool.c
index 88b27643c4a..fd3af145769 100644
--- 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;
 }
diff --git a/lib/isc/ratelimiter.c b/lib/isc/ratelimiter.c
index 8bee4e7e0fc..e4f8a0cfc24 100644
--- 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
diff --git a/lib/isc/symtab.c b/lib/isc/symtab.c
index 021d94c18c9..86fcc60dd41 100644
--- 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
diff --git a/lib/isc/task.c b/lib/isc/task.c
index f859849935d..f4dfeaec66a 100644
--- 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);
 }
diff --git a/lib/isc/taskpool.c b/lib/isc/taskpool.c
index e5c09dea4a6..95a4958e21d 100644
--- 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
diff --git a/lib/isc/unix/interfaceiter.c b/lib/isc/unix/interfaceiter.c
index c3da74a98f1..5797a848d06 100644
--- 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;
 }
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index eebce42f89d..d6c39502ce9 100644
--- 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
diff --git a/lib/isc/win32/interfaceiter.c b/lib/isc/win32/interfaceiter.c
index d8cbaa396e9..a135d3b0173 100644
--- 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;
 }
diff --git a/lib/isc/win32/socket.c b/lib/isc/win32/socket.c
index 2d2c67a6bb8..95ee49d8456 100644
--- 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
diff --git a/lib/isccc/sexpr.c b/lib/isccc/sexpr.c
index eae82aa5e1b..1e318329b01 100644
--- 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
diff --git a/lib/isccc/symtab.c b/lib/isccc/symtab.c
index 18bf32bdbc9..ffb2e8a52ea 100644
--- 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
diff --git a/lib/ns/client.c b/lib/ns/client.c
index a5867d09b1f..8762079524e 100644
--- 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 *
diff --git a/lib/ns/interfacemgr.c b/lib/ns/interfacemgr.c
index df1fe63aab5..f9da16483b9 100644
--- 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;
 }
 
 /*%
diff --git a/lib/ns/listenlist.c b/lib/ns/listenlist.c
index f198b5c847f..ee08c0cdf36 100644
--- 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
diff --git a/lib/ns/tests/nstest.c b/lib/ns/tests/nstest.c
index d4314693d2f..e05f8d8f550 100644
--- 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
diff --git a/lib/ns/xfrout.c b/lib/ns/xfrout.c
index 7ad4ef96ea7..391d4c12387 100644
--- 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