MDEV-30052 Crash with a query containing nested WINDOW clauses

Use SELECT_LEX to save lists for ORDER BY and GROUP BY before parsing
WINDOW clauses / specifications. This is needed for proper parsing
of a nested WINDOW clause when a WINDOW clause is used in a subquery
contained in another WINDOW clause.

Fix assignment of empty SQL_I_List to another one (in case of empty list
next shoud point on first).

6 files changed, 130 insertions, 17 deletions

diff --git a/mysql-test/main/win_orderby.result b/mysql-test/main/win_orderby.result
index bf4a40a4db3..1a9860c1c76 100644
--- a/mysql-test/main/win_orderby.result
+++ b/mysql-test/main/win_orderby.result
@@ -24,3 +24,66 @@ pk	count(a) over (order by pk rows between 2 preceding and 2 following)
 28	5
 27	5
 drop table t0,t1;
+#
+# MDEV-30052: Crash with a query containing nested WINDOW clauses
+#
+CREATE TABLE t1 (c INT);
+insert into t1 values (1),(2);
+UPDATE t1 SET c=1
+WHERE c=2
+ORDER BY
+(1 IN ((
+SELECT *
+FROM (SELECT * FROM t1) AS v1
+GROUP BY c
+WINDOW v2 AS (ORDER BY
+(SELECT *
+FROM t1
+GROUP BY c
+WINDOW v3 AS (PARTITION BY c)
+)
+)
+))
+);
+drop table t1;
+#
+# MDEV-29359: Server crashed with heap-use-after-free in
+# Field::is_null(long long) const (Just testcase)
+#
+CREATE TABLE t1 (id int);
+INSERT INTO t1 VALUES (-1),(0),(84);
+SELECT
+id IN (SELECT id
+FROM t1
+WINDOW w AS (ORDER BY (SELECT  1
+FROM t1
+WHERE
+EXISTS ( SELECT id
+FROM t1
+GROUP BY id
+WINDOW w2 AS (ORDER BY id)
+)
+)
+)
+)
+FROM t1;
+id IN (SELECT id
+FROM t1
+WINDOW w AS (ORDER BY (SELECT  1
+FROM t1
+WHERE
+EXISTS ( SELECT id
+FROM t1
+GROUP BY id
+WINDOW w2 AS (ORDER BY id)
+)
+)
+)
+)
+1
+1
+1
+DROP TABLE t1;
+#
+# End of 10.3 tests
+#
diff --git a/mysql-test/main/win_orderby.test b/mysql-test/main/win_orderby.test
index 7f02a582ea0..65421fc095c 100644
--- a/mysql-test/main/win_orderby.test
+++ b/mysql-test/main/win_orderby.test
@@ -33,3 +33,58 @@ limit 4;
 --disable_view_protocol
 
 drop table t0,t1;
+
+
+--echo #
+--echo # MDEV-30052: Crash with a query containing nested WINDOW clauses
+--echo #
+
+CREATE TABLE t1 (c INT);
+insert into t1 values (1),(2);
+UPDATE t1 SET c=1
+WHERE c=2
+ORDER BY
+  (1 IN ((
+      SELECT *
+      FROM (SELECT * FROM t1) AS v1
+      GROUP BY c
+      WINDOW v2 AS (ORDER BY
+                      (SELECT *
+                       FROM t1
+                       GROUP BY c
+                       WINDOW v3 AS (PARTITION BY c)
+                      )
+                    )
+    ))
+  );
+drop table t1;
+
+--echo #
+--echo # MDEV-29359: Server crashed with heap-use-after-free in
+--echo # Field::is_null(long long) const (Just testcase)
+--echo #
+
+CREATE TABLE t1 (id int);
+INSERT INTO t1 VALUES (-1),(0),(84);
+
+SELECT
+  id IN (SELECT id
+         FROM t1
+         WINDOW w AS (ORDER BY (SELECT  1
+                                FROM t1
+                                WHERE
+                                  EXISTS ( SELECT id
+                                           FROM t1
+                                           GROUP BY id
+                                           WINDOW w2 AS (ORDER BY id)
+                                          )
+                                )
+                      )
+         )
+FROM t1;
+
+DROP TABLE t1;
+
+--echo #
+--echo # End of 10.3 tests
+--echo #
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 5e4c41fe42c..a9adfebff81 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -755,8 +755,6 @@ void LEX::start(THD *thd_arg)
   stmt_var_list.empty();
   proc_list.elements=0;
 
-  save_group_list.empty();
-  save_order_list.empty();
   win_ref= NULL;
   win_frame= NULL;
   frame_top_bound= NULL;
@@ -2389,9 +2387,8 @@ void st_select_lex::init_select()
   ftfunc_list_alloc.empty();
   inner_sum_func_list= 0;
   ftfunc_list= &ftfunc_list_alloc;
-  order_list.elements= 0;
-  order_list.first= 0;
-  order_list.next= &order_list.first;
+  order_list.empty();
+
   /* Set limit and offset to default values */
   select_limit= 0;      /* denotes the default limit = HA_POS_ERROR */
   offset_limit= 0;      /* denotes the default offset = 0 */
diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index bdc8b5476b2..febe4cf459e 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -975,6 +975,7 @@ public:
     group_list_ptrs, and re-establish the original list before each execution.
   */
   SQL_I_List<ORDER>       group_list;
+  SQL_I_List<ORDER>       save_group_list;
   Group_list_ptrs        *group_list_ptrs;
 
   List<Item>          item_list;  /* list of fields & expressions */
@@ -1040,6 +1041,7 @@ public:
   const char *type;               /* type of select for EXPLAIN          */
 
   SQL_I_List<ORDER> order_list;   /* ORDER clause */
+  SQL_I_List<ORDER> save_order_list;
   SQL_I_List<ORDER> gorder_list;
   Item *select_limit, *offset_limit;  /* LIMIT clause parameters */
 
@@ -1249,9 +1251,7 @@ public:
   void set_lock_for_tables(thr_lock_type lock_type, bool for_update);
   inline void init_order()
   {
-    order_list.elements= 0;
-    order_list.first= 0;
-    order_list.next= &order_list.first;
+    order_list.empty();
   }
   /*
     This method created for reiniting LEX in mysql_admin_table() and can be
@@ -3215,8 +3215,6 @@ public:
   }
 
 
-  SQL_I_List<ORDER> save_group_list;
-  SQL_I_List<ORDER> save_order_list;
   LEX_CSTRING *win_ref;
   Window_frame *win_frame;
   Window_frame_bound *frame_top_bound;
diff --git a/sql/sql_list.h b/sql/sql_list.h
index b11239856f5..e2b65dcad14 100644
--- a/sql/sql_list.h
+++ b/sql/sql_list.h
@@ -53,7 +53,7 @@ public:
   {
     elements= tmp.elements;
     first= tmp.first;
-    next= tmp.next;
+    next= elements ? tmp.next : &first;;
     return *this;
   }
 
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 3102aa69b86..f360b246cce 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -8662,8 +8662,8 @@ TABLE_LIST *st_select_lex::convert_right_join()
 void st_select_lex::prepare_add_window_spec(THD *thd)
 {
   LEX *lex= thd->lex;
-  lex->save_group_list= group_list;
-  lex->save_order_list= order_list;
+  save_group_list= group_list;
+  save_order_list= order_list;
   lex->win_ref= NULL;
   lex->win_frame= NULL;
   lex->frame_top_bound= NULL;
@@ -8690,8 +8690,8 @@ bool st_select_lex::add_window_def(THD *thd,
                                                       win_part_list_ptr,
                                                       win_order_list_ptr,
                                                       win_frame);
-  group_list= thd->lex->save_group_list;
-  order_list= thd->lex->save_order_list;
+  group_list= save_group_list;
+  order_list= save_order_list;
   if (parsing_place != SELECT_LIST)
   {
     fields_in_window_functions+= win_part_list_ptr->elements +
@@ -8717,8 +8717,8 @@ bool st_select_lex::add_window_spec(THD *thd,
                                                          win_part_list_ptr,
                                                          win_order_list_ptr,
                                                          win_frame);
-  group_list= thd->lex->save_group_list;
-  order_list= thd->lex->save_order_list;
+  group_list= save_group_list;
+  order_list= save_order_list;
   if (parsing_place != SELECT_LIST)
   {
     fields_in_window_functions+= win_part_list_ptr->elements +