--- source3/passdb/lookup_sid.c.ORIG	2021-01-26 16:25:59.235435000 +0100
+++ source3/passdb/lookup_sid.c	2021-01-26 19:31:37.547397000 +0100
@@ -1247,7 +1247,7 @@
 {
 	struct wbcDomainSid *wbc_sids = NULL;
 	struct wbcUnixId *wbc_ids = NULL;
-	uint32_t i, num_not_cached;
+	uint32_t i, num_not_cached, num_not_cached_size, cached_not_specified;
 	wbcErr err;
 	bool ret = false;
 
@@ -1257,7 +1257,8 @@
 	}
 
 	num_not_cached = 0;
-
+	cached_not_specified = 0;
+	
 	for (i=0; i<num_sids; i++) {
 		bool expired;
 		uint32_t rid;
@@ -1277,6 +1278,9 @@
 		if (idmap_cache_find_sid2unixid(&sids[i], &ids[i], &expired)
 		    && !expired)
 		{
+		  if (ids[i].type == ID_TYPE_NOT_SPECIFIED)
+		    cached_not_specified++;
+		  
 			continue;
 		}
 		ids[i].type = ID_TYPE_NOT_SPECIFIED;
@@ -1287,6 +1291,10 @@
 	if (num_not_cached == 0) {
 		goto done;
 	}
+	if (cached_not_specified > 0)
+	  DEBUG(1, ("DANGER, WILL ROBINSON, DANGER! (cached_not_specified=%d, num_not_cached=%d)\n",
+		    cached_not_specified, num_not_cached));
+	num_not_cached_size = num_not_cached;
 	wbc_ids = talloc_array(talloc_tos(), struct wbcUnixId, num_not_cached);
 	if (wbc_ids == NULL) {
 		goto fail;
@@ -1304,6 +1312,11 @@
 
 	for (i=0; i<num_sids; i++) {
 		if (ids[i].type == ID_TYPE_NOT_SPECIFIED) {
+		  if (num_not_cached >= num_not_cached_size) {
+		    DEBUG(1, ("ERROR - num_not_cached(%d) >= num_not_cached_size(%d), i=%d, num_sids=%d\n",
+			      num_not_cached, num_not_cached_size, i, num_sids));
+		    goto fail;
+		  }
 			switch (wbc_ids[num_not_cached].type) {
 			case WBC_ID_TYPE_UID:
 				ids[i].type = ID_TYPE_UID;