diff --git a/contrib/pgcrypto/px.c b/contrib/pgcrypto/px.c
index 4205e9c3ef..2099ce2a7a 100644
--- a/contrib/pgcrypto/px.c
+++ b/contrib/pgcrypto/px.c
@@ -200,7 +200,7 @@ combo_init(PX_Combo *cx, const uint8 *key, unsigned klen,
 		ivbuf = palloc0(ivs);
 		if (ivlen > ivs)
 			memcpy(ivbuf, iv, ivs);
-		else
+		else if (ivlen > 0)
 			memcpy(ivbuf, iv, ivlen);
 	}
 
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index de787c3d37..eca1e5dd0e 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -294,7 +294,7 @@ TransactionIdSetPageStatus(TransactionId xid, int nsubxids,
 	 * sub-XIDs and all of the XIDs for which we're adjusting clog should be
 	 * on the same page.  Check those conditions, too.
 	 */
-	if (all_xact_same_page && xid == MyProc->xid &&
+	if (subxids != NULL && all_xact_same_page && xid == MyProc->xid &&
 		nsubxids <= THRESHOLD_SUBTRANS_CLOG_OPT &&
 		nsubxids == MyProc->subxidStatus.count &&
 		memcmp(subxids, MyProc->subxids.xids,
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index c9516e03fa..3d5ca89d42 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -5329,7 +5329,7 @@ SerializeTransactionState(Size maxsize, char *start_address)
 	 * of our own, we can just pass along the information that was passed to
 	 * us.
 	 */
-	if (nParallelCurrentXids > 0)
+	if (nParallelCurrentXids > 0 && ParallelCurrentXids != NULL)
 	{
 		result->nParallelCurrentXids = nParallelCurrentXids;
 		memcpy(&result->parallelCurrentXids[0], ParallelCurrentXids,
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index e5cf1bde13..ae10c55711 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -1182,7 +1182,10 @@ DefineIndex(Oid relationId,
 			pgstat_progress_update_param(PROGRESS_CREATEIDX_PARTITIONS_TOTAL,
 										 nparts);
 
-			memcpy(part_oids, partdesc->oids, sizeof(Oid) * nparts);
+			if (partdesc->oids != NULL)
+			{
+				memcpy(part_oids, partdesc->oids, sizeof(Oid) * nparts);
+			}
 
 			parentDesc = RelationGetDescr(rel);
 			opfamOids = palloc(sizeof(Oid) * numberOfKeyAttributes);