MDEV-16603 Crash with set join_cache_level=4

When the definition of the index used for hash join was created
in create_hj_key_for_table() it could cause memory overwrite
due to a bug that led to an underestimation of the number of
the index component.

mysql-test/r/join_cache.result

@@ -5871,4 +5871,37 @@ SET join_buffer_size = default;
 SET join_buffer_space_limit= default;
 set optimizer_switch=@save_optimizer_switch;
 DROP TABLE t1,t4,t5,t2;
+#
+# MDEV-16603: BNLH for query with materialized semi-join
+#
+set join_cache_level=4;
+CREATE TABLE t1 ( i1 int, v1 varchar(1)) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (7,'x');
+CREATE TABLE t2 (i1 int, v1 varchar(1), KEY v1 (v1,i1)) ENGINE=InnoDB;
+INSERT INTO t2 VALUES
+(NULL,'x'),(1,'x'),(3,'x'),(5,'x'),(8,'x'),(48,'x'),
+(228,'x'),(3,'y'),(1,'z'),(9,'z');
+CREATE TABLE temp
+SELECT t1.i1 AS f1, t1.v1 AS f2 FROM (t2 JOIN t1 ON (t1.v1 = t2.v1));
+SELECT * FROM temp
+WHERE (f1,f2) IN (SELECT t1.i1, t1.v1 FROM (t2 JOIN t1 ON (t1.v1 = t2.v1)));
+f1	f2
+7	x
+7	x
+7	x
+7	x
+7	x
+7	x
+7	x
+EXPLAIN EXTENDED SELECT * FROM temp
+WHERE (f1,f2) IN (SELECT t1.i1, t1.v1 FROM (t2 JOIN t1 ON (t1.v1 = t2.v1)));
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	1	100.00	
+1	PRIMARY	temp	hash_ALL	NULL	#hash#$hj	9	test.t1.i1,test.t1.v1	7	100.00	Using where; Using join buffer (flat, BNLH join)
+2	MATERIALIZED	t1	ALL	NULL	NULL	NULL	NULL	1	100.00	Using where
+2	MATERIALIZED	t2	hash_index	v1	#hash#v1:v1	4:9	test.t1.v1	10	10.00	Using join buffer (flat, BNLH join)
+Warnings:
+Note	1003	select `test`.`temp`.`f1` AS `f1`,`test`.`temp`.`f2` AS `f2` from `test`.`temp` semi join (`test`.`t2` join `test`.`t1`) where ((`test`.`temp`.`f1` = `test`.`t1`.`i1`) and (`test`.`t2`.`v1` = `test`.`t1`.`v1`) and (`test`.`temp`.`f2` = `test`.`t1`.`v1`))
+DROP TABLE t1,t2,temp;
+SET join_cache_level = default;
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/t/join_cache.test

@@ -3836,5 +3836,36 @@ set optimizer_switch=@save_optimizer_switch;
 
 DROP TABLE t1,t4,t5,t2;
 
+--echo #
+--echo # MDEV-16603: BNLH for query with materialized semi-join
+--echo #
+
+--source include/have_innodb.inc
+
+set join_cache_level=4;
+
+CREATE TABLE t1 ( i1 int, v1 varchar(1)) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (7,'x');
+
+CREATE TABLE t2 (i1 int, v1 varchar(1), KEY v1 (v1,i1)) ENGINE=InnoDB;
+
+INSERT INTO t2 VALUES
+ (NULL,'x'),(1,'x'),(3,'x'),(5,'x'),(8,'x'),(48,'x'),
+ (228,'x'),(3,'y'),(1,'z'),(9,'z');
+
+CREATE TABLE temp
+SELECT t1.i1 AS f1, t1.v1 AS f2 FROM (t2 JOIN t1 ON (t1.v1 = t2.v1));
+
+let $q =
+SELECT * FROM temp
+WHERE (f1,f2) IN (SELECT t1.i1, t1.v1 FROM (t2 JOIN t1 ON (t1.v1 = t2.v1)));
+
+eval $q;
+eval EXPLAIN EXTENDED $q;
+
+DROP TABLE t1,t2,temp;
+
+SET join_cache_level = default;
+
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;

sql/sql_select.cc

@@ -7994,7 +7994,6 @@ static bool create_hj_key_for_table(JOIN *join, JOIN_TAB *join_tab,
       if (first_keyuse)
       {
         key_parts++;
-        first_keyuse= FALSE;
       }
       else
       {
@@ -8004,14 +8003,15 @@ static bool create_hj_key_for_table(JOIN *join, JOIN_TAB *join_tab,
           if (curr->keypart == keyuse->keypart &&
               !(~used_tables & curr->used_tables) &&
               join_tab->keyuse_is_valid_for_access_in_chosen_plan(join,
-                                                                  keyuse) &&
+                                                                  curr) &&
               are_tables_local(join_tab, curr->used_tables))
             break;
         }
         if (curr == keyuse)
            key_parts++;
       }
     }
+    first_keyuse= FALSE;
     keyuse++;
   } while (keyuse->table == table && keyuse->is_for_hash_join());
   if (!key_parts)