MDEV-32466: Potential memory leak on executing of create view statement

This patch is actually follow-up for the task
  MDEV-23902: MariaDB crash on calling function
to use correct query arena for a statement. In case invocation of
a function is in progress use its call arena, else use current
query arena that can be either a statement or a regular query arena.

mysql-test/main/ps_mem_leaks.result

@@ -57,4 +57,26 @@ EXECUTE stmt;
 exp
 0
 DEALLOCATE PREPARE stmt;
+#
+# MDEV-32466: Potential memory leak on execuing of create view statement
+#
+CREATE FUNCTION f1 () RETURNS VARCHAR(1)
+BEGIN
+DECLARE rec1 ROW TYPE OF v1;
+SELECT z INTO rec1 FROM v1;
+RETURN 1;
+END|
+CREATE FUNCTION f2 () RETURNS VARCHAR(1) RETURN '!';
+CREATE VIEW v1 AS SELECT f2() z;
+PREPARE stmt FROM "SELECT f1()";
+EXECUTE stmt;
+f1()
+1
+EXECUTE stmt;
+f1()
+1
+DEALLOCATE PREPARE stmt;
+DROP FUNCTION f1;
+DROP VIEW v1;
+DROP FUNCTION f2;
 # End of 10.4 tests

mysql-test/main/ps_mem_leaks.test

@@ -69,4 +69,32 @@ EXECUTE stmt;
 
 DEALLOCATE PREPARE stmt;
 
+--echo #
+--echo # MDEV-32466: Potential memory leak on execuing of create view statement
+--echo #
+
+--delimiter |
+
+CREATE FUNCTION f1 () RETURNS VARCHAR(1)
+BEGIN
+  DECLARE rec1 ROW TYPE OF v1;
+  SELECT z INTO rec1 FROM v1;
+  RETURN 1;
+END|
+--delimiter ;
+
+CREATE FUNCTION f2 () RETURNS VARCHAR(1) RETURN '!';
+CREATE VIEW v1 AS SELECT f2() z;
+
+PREPARE stmt FROM "SELECT f1()";
+EXECUTE stmt;
+EXECUTE stmt;
+
+DEALLOCATE PREPARE stmt;
+
+# Clean up
+DROP FUNCTION f1;
+DROP VIEW v1;
+DROP FUNCTION f2;
+
 --echo # End of 10.4 tests

sql/sp.cc

@@ -2720,7 +2720,8 @@ void sp_update_stmt_used_routines(THD *thd, Query_tables_list *prelocking_ctx,
                                   TABLE_LIST *belong_to_view)
 {
   for (Sroutine_hash_entry *rt= src->first; rt; rt= rt->next)
-    (void)sp_add_used_routine(prelocking_ctx, thd->stmt_arena,
+
+    (void)sp_add_used_routine(prelocking_ctx, thd->active_stmt_arena_to_use(),
                               &rt->mdl_request.key, rt->m_handler,
                               belong_to_view);
 }

sql/sql_base.cc

@@ -7740,7 +7740,7 @@ bool setup_fields(THD *thd, Ref_ptr_array ref_pointer_array,
   while ((item= it++))
   {
     if (make_pre_fix)
-      pre_fix->push_back(item, thd->stmt_arena->mem_root);
+      pre_fix->push_back(item, thd->active_stmt_arena_to_use()->mem_root);
 
     if (item->fix_fields_if_needed_for_scalar(thd, it.ref()))
     {

sql/sql_class.h

@@ -2790,6 +2790,17 @@ class THD: public THD_count, /* this must be first */
   */
   Query_arena *stmt_arena;
 
+  /**
+    Get either call or statement arena. In case some function is called from
+    within a query the call arena has to be used for a memory allocation,
+    else use the statement arena.
+  */
+  Query_arena *active_stmt_arena_to_use()
+  {
+    return (state  == Query_arena::STMT_SP_QUERY_ARGUMENTS) ? this :
+                                                              stmt_arena;
+  }
+
   void *bulk_param;
 
   /*

sql/sql_lex.cc

@@ -3115,8 +3115,9 @@ bool st_select_lex::setup_ref_array(THD *thd, uint order_group_num)
   uint n_elems= get_cardinality_of_ref_ptrs_slice(order_group_num) * 5;
   if (!ref_pointer_array.is_null())
     return false;
-  Item **array= static_cast<Item**>(thd->stmt_arena->alloc(sizeof(Item*) *
-                                                           n_elems));
+
+  Item **array= static_cast<Item**>(
+    thd->active_stmt_arena_to_use()->alloc(sizeof(Item*) * n_elems));
   if (likely(array != NULL))
     ref_pointer_array= Ref_ptr_array(array, n_elems);
   return array == NULL;

sql/sql_view.cc

@@ -1655,7 +1655,7 @@ bool mysql_make_view(THD *thd, TABLE_SHARE *share, TABLE_LIST *table,
         objects of the view.
       */
       if (!(table->view_sctx= (Security_context *)
-            thd->stmt_arena->calloc(sizeof(Security_context))))
+            thd->active_stmt_arena_to_use()->calloc(sizeof(Security_context))))
         goto err;
       security_ctx= table->view_sctx;
     }