MDEV-24823 Crash with invalid multi-table update of view in 2nd execution of SP

Before this patch mergeable derived tables / view used in a multi-table
update / delete were merged before the preparation stage.
When the merge of a derived table / view is performed the on expression
attached to it is fixed and ANDed with the where condition of the select S
containing this derived table / view. It happens after the specification of
the derived table / view has been merged into S. If the ON expression refers
to a non existing field an error is reported and some other mergeable derived
tables / views remain unmerged. It's not a problem if the multi-table
update / delete statement is standalone. Yet if it is used in a stored
procedure the select with incompletely merged derived tables / views may
cause a problem for the second call of the procedure. This does not happen
for select queries using derived tables / views, because in this case their
specifications are merged after the preparation stage at which all ON
expressions are fixed.
This patch makes sure that merging of the derived tables / views used in a
multi-table update / delete statement is performed after the preparation
stage.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/sql/sql_class.h b/sql/sql_class.h
index 5ab93de7957..4f0df744b92 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -6117,7 +6117,8 @@ public:
 class multi_update :public select_result_interceptor
 {
   TABLE_LIST *all_tables; /* query/update command tables */
-  List<TABLE_LIST> *leaves;     /* list of leves of join table tree */
+  List<TABLE_LIST> *leaves;     /* list of leaves of join table tree */
+  List<TABLE_LIST> updated_leaves;  /* list of of updated leaves */
   TABLE_LIST *update_tables;
   TABLE **tmp_tables, *main_table, *table_to_update;
   TMP_TABLE_PARAM *tmp_table_param;
@@ -6155,6 +6156,7 @@ public:
 	       List<Item> *fields, List<Item> *values,
 	       enum_duplicates handle_duplicates, bool ignore);
   ~multi_update();
+  bool init(THD *thd);
   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   int send_data(List<Item> &items);
   bool initialize_tables (JOIN *join);