MDEV-21603 Crashing SHOW TABLES with derived table in WHERE condition

When you only need view structure, don't call handle_derived with
DT_CREATE and rely on its internal hackish check to skip DT_CREATE.
Because handle_derived is called from many different places,
and this internal hackish check is indiscriminative.

Instead, just don't ask handle_derived to do DT_CREATE
if you don't want it to do DT_CREATE.

mysql-test/r/show.result

+#
+# MDEV-9538 Server crashes in check_show_access on SHOW STATISTICS
+# MDEV-9539 Server crashes in make_columns_old_format on SHOW GEOMETRY_COLUMNS
+# MDEV-9540 SHOW SPATIAL_REF_SYS and SHOW SYSTEM_VARIABLES return empty results with numerous warnings
+#
 show statistics;
 ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'statistics' at line 1
 show spatial_ref_sys
@@ -10,3 +15,30 @@ show geometry_columns;
 ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'geometry_columns' at line 1
 show nonexistent;
 ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'nonexistent' at line 1
+#
+# MDEV-21603 Crashing SHOW TABLES with derived table in WHERE condition
+#
+create table t1 (nm varchar(32), a int);
+insert t1 values ('1',1),('2',2),('3',3);
+show tables
+where tables_in_test in (select *
+from (select nm from test.t1 group by nm) dt);
+Tables_in_test
+show fields from test.t1
+where field in (select * from (select nm from test.t1 group by nm) dt);
+Field	Type	Null	Key	Default	Extra
+insert t1 values ('nm',0);
+show fields from test.t1
+where field in (select * from (select nm from test.t1 group by nm) dt);
+Field	Type	Null	Key	Default	Extra
+nm	varchar(32)	YES		NULL	
+show fields from test.t1 where field in
+(select * from (select column_name from information_schema.columns
+where table_name='t1' group by column_name) dt);
+Field	Type	Null	Key	Default	Extra
+nm	varchar(32)	YES		NULL	
+a	int(11)	YES		NULL	
+drop table t1;
+#
+# End of 10.2 tests
+#

mysql-test/t/show.test

-#
-# MDEV-9538 Server crashes in check_show_access on SHOW STATISTICS
-# MDEV-9539 Server crashes in make_columns_old_format on SHOW GEOMETRY_COLUMNS
-# MDEV-9540 SHOW SPATIAL_REF_SYS and SHOW SYSTEM_VARIABLES return empty results with numerous warnings
-#
+--echo #
+--echo # MDEV-9538 Server crashes in check_show_access on SHOW STATISTICS
+--echo # MDEV-9539 Server crashes in make_columns_old_format on SHOW GEOMETRY_COLUMNS
+--echo # MDEV-9540 SHOW SPATIAL_REF_SYS and SHOW SYSTEM_VARIABLES return empty results with numerous warnings
+--echo #
 --error ER_PARSE_ERROR
 show statistics;
 --error ER_PARSE_ERROR
@@ -13,3 +13,27 @@ show system_variables;
 show geometry_columns;
 --error ER_PARSE_ERROR
 show nonexistent;
+
+--echo #
+--echo # MDEV-21603 Crashing SHOW TABLES with derived table in WHERE condition
+--echo #
+create table t1 (nm varchar(32), a int);
+insert t1 values ('1',1),('2',2),('3',3);
+
+show tables
+  where tables_in_test in (select *
+                              from (select nm from test.t1 group by nm) dt);
+show fields from test.t1
+   where field in (select * from (select nm from test.t1 group by nm) dt);
+insert t1 values ('nm',0);
+show fields from test.t1
+   where field in (select * from (select nm from test.t1 group by nm) dt);
+
+show fields from test.t1 where field in
+        (select * from (select column_name from information_schema.columns
+                          where table_name='t1' group by column_name) dt);
+drop table t1;
+
+--echo #
+--echo # End of 10.2 tests
+--echo #

sql/sql_base.cc

@@ -4939,7 +4939,6 @@ bool open_normal_and_derived_tables(THD *thd, TABLE_LIST *tables, uint flags,
   uint counter;
   MDL_savepoint mdl_savepoint= thd->mdl_context.mdl_savepoint();
   DBUG_ENTER("open_normal_and_derived_tables");
-  DBUG_ASSERT(!thd->fill_derived_tables());
   if (open_tables(thd, &tables, &counter, flags, &prelocking_strategy) ||
       mysql_handle_derived(thd->lex, dt_phases))
     goto end;

sql/sql_class.h

@@ -3469,10 +3469,6 @@ class THD :public Statement,
   {
     return server_status & SERVER_STATUS_IN_TRANS;
   }
-  inline bool fill_derived_tables()
-  {
-    return !stmt_arena->is_stmt_prepare() && !lex->only_view_structure();
-  }
   inline bool fill_information_schema_tables()
   {
     return !stmt_arena->is_stmt_prepare();

sql/sql_derived.cc

@@ -70,7 +70,6 @@ bool
 mysql_handle_derived(LEX *lex, uint phases)
 {
   bool res= FALSE;
-  THD *thd= lex->thd;
   DBUG_ENTER("mysql_handle_derived");
   DBUG_PRINT("enter", ("phases: 0x%x", phases));
   if (!lex->derived_tables)
@@ -85,8 +84,6 @@ mysql_handle_derived(LEX *lex, uint phases)
       break;
     if (!(phases & phase_flag))
       continue;
-    if (phase_flag >= DT_CREATE && !thd->fill_derived_tables())
-      break;
 
     for (SELECT_LEX *sl= lex->all_selects_list;
 	 sl && !res;
@@ -169,7 +166,6 @@ bool
 mysql_handle_single_derived(LEX *lex, TABLE_LIST *derived, uint phases)
 {
   bool res= FALSE;
-  THD *thd= lex->thd;
   uint8 allowed_phases= (derived->is_merged_derived() ? DT_PHASES_MERGE :
                          DT_PHASES_MATERIALIZE);
   DBUG_ENTER("mysql_handle_single_derived");
@@ -192,8 +188,6 @@ mysql_handle_single_derived(LEX *lex, TABLE_LIST *derived, uint phases)
     if (phase_flag != DT_PREPARE &&
         !(allowed_phases & phase_flag))
       continue;
-    if (phase_flag >= DT_CREATE && !thd->fill_derived_tables())
-      break;
 
     if ((res= (*processors[phase])(lex->thd, lex, derived)))
       break;
@@ -1376,4 +1370,3 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived)
   thd->lex->current_select= save_curr_select;
   DBUG_RETURN(false);
 }
-

sql/sql_prepare.cc

@@ -1659,7 +1659,7 @@ static int mysql_test_select(Prepared_statement *stmt,
   }
 
   if (open_normal_and_derived_tables(thd, tables,  MYSQL_OPEN_FORCE_SHARED_MDL,
-                                     DT_INIT | DT_PREPARE | DT_CREATE))
+                                     DT_INIT | DT_PREPARE))
     goto error;
 
   thd->lex->used_tables= 0;                        // Updated by setup_fields
@@ -1721,7 +1721,7 @@ static bool mysql_test_do_fields(Prepared_statement *stmt,
     DBUG_RETURN(TRUE);
 
   if (open_normal_and_derived_tables(thd, tables, MYSQL_OPEN_FORCE_SHARED_MDL,
-                                     DT_INIT | DT_PREPARE | DT_CREATE))
+                                     DT_INIT | DT_PREPARE))
     DBUG_RETURN(TRUE);
   DBUG_RETURN(setup_fields(thd, Ref_ptr_array(),
                            *values, MARK_COLUMNS_NONE, 0, NULL, 0));
@@ -1753,7 +1753,7 @@ static bool mysql_test_set_fields(Prepared_statement *stmt,
   if ((tables &&
        check_table_access(thd, SELECT_ACL, tables, FALSE, UINT_MAX, FALSE)) ||
       open_normal_and_derived_tables(thd, tables, MYSQL_OPEN_FORCE_SHARED_MDL,
-                                     DT_INIT | DT_PREPARE | DT_CREATE))
+                                     DT_INIT | DT_PREPARE))
     goto error;
 
   while ((var= it++))
@@ -1918,7 +1918,7 @@ static bool mysql_test_create_table(Prepared_statement *stmt)
 
     if (open_normal_and_derived_tables(stmt->thd, lex->query_tables,
                                        MYSQL_OPEN_FORCE_SHARED_MDL,
-                                       DT_INIT | DT_PREPARE | DT_CREATE))
+                                       DT_INIT | DT_PREPARE))
       DBUG_RETURN(TRUE);
 
     select_lex->context.resolve_in_select_list= TRUE;

sql/sql_show.cc

@@ -1528,7 +1528,7 @@ mysqld_list_fields(THD *thd, TABLE_LIST *table_list, const char *wild)
 
   if (open_normal_and_derived_tables(thd, table_list,
                                      MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL,
-                                     DT_INIT | DT_PREPARE | DT_CREATE))
+                                     DT_INIT | DT_PREPARE))
     DBUG_VOID_RETURN;
   table= table_list->table;
 
@@ -4414,7 +4414,7 @@ fill_schema_table_by_open(THD *thd, bool is_show_fields_or_keys,
                                            MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL |
                                            (can_deadlock ?
                                             MYSQL_OPEN_FAIL_ON_MDL_CONFLICT : 0)),
-					  DT_INIT | DT_PREPARE | DT_CREATE));
+					  DT_INIT | DT_PREPARE));
 
   /*
     Restore old value of sql_command back as it is being looked at in