BUG#18198: Too much expressiveness in partition function allowed

Fixed the error check

sql/partition_info.cc

@@ -658,8 +658,13 @@ bool partition_info::check_partition_info(handlerton **eng_type,
   bool part_expression_ok= TRUE;
   DBUG_ENTER("partition_info::check_partition_info");
 
-  if (part_expr->walk(Item::check_partition_func_processor,
-                      (byte*)&part_expression_ok))
+  if (part_type != HASH_PARTITION || !list_of_part_fields)
+    part_expr->walk(Item::check_partition_func_processor,
+                    (byte*)&part_expression_ok);
+  if (is_sub_partitioned() && !list_of_subpart_fields)
+    subpart_expr->walk(Item::check_partition_func_processor,
+                       (byte*)&part_expression_ok);
+  if (!part_expression_ok)
   {
     my_error(ER_PARTITION_FUNC_NOT_ALLOWED, MYF(0));
     goto end;