--- glibc-2.34.orig/nss/XXX-lookup.c	2021-12-02 10:57:55.785033000 +0100
+++ glibc-2.34/nss/XXX-lookup.c	2021-12-02 10:59:22.796033000 +0100
@@ -53,6 +53,9 @@
   if (! __nss_database_get (DATABASE_NAME_ID, &DATABASE_NAME_SYMBOL))
     return -1;
 
+  if (!DATABASE_NAME_SYMBOL)
+    return -1;
+
   *ni = DATABASE_NAME_SYMBOL;
 
   return __nss_lookup (ni, fct_name, fct2_name, fctp);