Fixed LP bug#684086.

If a primary key was used in the index intersection for
an InnoDB database the size of the memory allocated
for the best index intersection plan was one element less
than it was needed. That could cause a memory overwrite
and a crash as a result of it.
  

mysql-test/r/index_intersect.result

@@ -1013,4 +1013,40 @@ ID	Name	Country	Population
 1910	Changsha	CHN	1809800
 DROP DATABASE world;
 use test;
+CREATE TABLE t1 (
+f1 int,
+f4 varchar(32),
+f5 int,
+PRIMARY KEY (f1),
+KEY (f4)
+) ENGINE=InnoDB;
+Warnings:
+Warning	1286	Unknown table engine 'InnoDB'
+Warning	1266	Using storage engine MyISAM for table 't1'
+INSERT INTO t1 VALUES 
+(5,'H',1), (9,'g',0), (527,'i',0), (528,'y',1), (529,'S',6),
+(530,'m',7), (531,'b',2), (532,'N',1), (533,'V',NULL), (534,'l',1),
+(535,'M',0), (536,'w',1), (537,'j',5), (538,'l',0), (539,'n',2),
+(540,'m',2), (541,'r',2), (542,'l',2), (543,'h',3),(544,'o',0),
+(956,'h',0), (957,'g',0), (958,'W',5), (959,'s',3), (960,'w',0),
+(961,'q',0), (962,'e',NULL), (963,'u',7), (964,'q',1), (965,'N',NULL),
+(966,'e',0), (967,'t',3), (968,'e',6), (969,'f',NULL), (970,'j',0),
+(971,'s',3), (972,'I',0), (973,'h',4), (974,'g',1), (975,'s',0),
+(976,'r',3), (977,'x',1), (978,'v',8), (979,'j',NULL), (980,'z',7),
+(981,'t',9), (982,'j',5), (983,'u',NULL), (984,'g',6), (985,'w',1),
+(986,'h',1), (987,'v',0), (988,'v',0), (989,'c',2), (990,'b',7),
+(991,'z',0), (992,'M',1), (993,'u',2), (994,'r',2), (995,'b',4),
+(996,'A',2), (997,'u',0), (998,'a',0), (999,'j',2), (1,'I',2);
+EXPLAIN
+SELECT * FROM t1
+WHERE (f1 < 535  OR  f1 > 985) AND ( f4='r' OR f4 LIKE 'a%' ) ;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	PRIMARY,f4	f4	35	NULL	5	Using where
+SELECT * FROM t1
+WHERE (f1 < 535  OR  f1 > 985) AND ( f4='r' OR f4 LIKE 'a%' ) ;
+f1	f4	f5
+996	A	2
+998	a	0
+994	r	2
+DROP TABLE t1;
 SET SESSION optimizer_switch='index_merge_sort_intersection=on';

mysql-test/r/index_intersect_innodb.result

@@ -1014,5 +1014,38 @@ ID	Name	Country	Population
 1910	Changsha	CHN	1809800
 DROP DATABASE world;
 use test;
+CREATE TABLE t1 (
+f1 int,
+f4 varchar(32),
+f5 int,
+PRIMARY KEY (f1),
+KEY (f4)
+) ENGINE=InnoDB;
+INSERT INTO t1 VALUES 
+(5,'H',1), (9,'g',0), (527,'i',0), (528,'y',1), (529,'S',6),
+(530,'m',7), (531,'b',2), (532,'N',1), (533,'V',NULL), (534,'l',1),
+(535,'M',0), (536,'w',1), (537,'j',5), (538,'l',0), (539,'n',2),
+(540,'m',2), (541,'r',2), (542,'l',2), (543,'h',3),(544,'o',0),
+(956,'h',0), (957,'g',0), (958,'W',5), (959,'s',3), (960,'w',0),
+(961,'q',0), (962,'e',NULL), (963,'u',7), (964,'q',1), (965,'N',NULL),
+(966,'e',0), (967,'t',3), (968,'e',6), (969,'f',NULL), (970,'j',0),
+(971,'s',3), (972,'I',0), (973,'h',4), (974,'g',1), (975,'s',0),
+(976,'r',3), (977,'x',1), (978,'v',8), (979,'j',NULL), (980,'z',7),
+(981,'t',9), (982,'j',5), (983,'u',NULL), (984,'g',6), (985,'w',1),
+(986,'h',1), (987,'v',0), (988,'v',0), (989,'c',2), (990,'b',7),
+(991,'z',0), (992,'M',1), (993,'u',2), (994,'r',2), (995,'b',4),
+(996,'A',2), (997,'u',0), (998,'a',0), (999,'j',2), (1,'I',2);
+EXPLAIN
+SELECT * FROM t1
+WHERE (f1 < 535  OR  f1 > 985) AND ( f4='r' OR f4 LIKE 'a%' ) ;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	PRIMARY,f4	PRIMARY,f4	4,35	NULL	1	Using sort_intersect(PRIMARY,f4); Using where
+SELECT * FROM t1
+WHERE (f1 < 535  OR  f1 > 985) AND ( f4='r' OR f4 LIKE 'a%' ) ;
+f1	f4	f5
+994	r	2
+996	A	2
+998	a	0
+DROP TABLE t1;
 SET SESSION optimizer_switch='index_merge_sort_intersection=on';
 SET SESSION STORAGE_ENGINE=DEFAULT;

mysql-test/t/index_intersect.test

@@ -379,4 +379,41 @@ DROP DATABASE world;
 
 use test;
 
+#
+# Bug #684086: crash with EXPLAIN in InnoDB for index intersection
+#              of two indexes one of which is primary
+#
+
+CREATE TABLE t1 (
+  f1 int,
+  f4 varchar(32),
+  f5 int,
+  PRIMARY KEY (f1),
+  KEY (f4)
+) ENGINE=InnoDB;
+
+INSERT INTO t1 VALUES 
+  (5,'H',1), (9,'g',0), (527,'i',0), (528,'y',1), (529,'S',6),
+  (530,'m',7), (531,'b',2), (532,'N',1), (533,'V',NULL), (534,'l',1),
+  (535,'M',0), (536,'w',1), (537,'j',5), (538,'l',0), (539,'n',2),
+  (540,'m',2), (541,'r',2), (542,'l',2), (543,'h',3),(544,'o',0),
+  (956,'h',0), (957,'g',0), (958,'W',5), (959,'s',3), (960,'w',0),
+  (961,'q',0), (962,'e',NULL), (963,'u',7), (964,'q',1), (965,'N',NULL),
+  (966,'e',0), (967,'t',3), (968,'e',6), (969,'f',NULL), (970,'j',0),
+  (971,'s',3), (972,'I',0), (973,'h',4), (974,'g',1), (975,'s',0),
+  (976,'r',3), (977,'x',1), (978,'v',8), (979,'j',NULL), (980,'z',7),
+  (981,'t',9), (982,'j',5), (983,'u',NULL), (984,'g',6), (985,'w',1),
+  (986,'h',1), (987,'v',0), (988,'v',0), (989,'c',2), (990,'b',7),
+  (991,'z',0), (992,'M',1), (993,'u',2), (994,'r',2), (995,'b',4),
+  (996,'A',2), (997,'u',0), (998,'a',0), (999,'j',2), (1,'I',2);
+
+EXPLAIN
+SELECT * FROM t1
+WHERE (f1 < 535  OR  f1 > 985) AND ( f4='r' OR f4 LIKE 'a%' ) ;
+
+SELECT * FROM t1
+WHERE (f1 < 535  OR  f1 > 985) AND ( f4='r' OR f4 LIKE 'a%' ) ;
+
+DROP TABLE t1;
+
 SET SESSION optimizer_switch='index_merge_sort_intersection=on';

sql/opt_range.cc

@@ -4995,7 +4995,8 @@ bool prepare_search_best_index_intersect(PARAM *param,
 
   if (!(common->best_intersect=
 	(INDEX_SCAN_INFO **) alloc_root (param->mem_root,
-                                         sizeof(INDEX_SCAN_INFO *) * i)))
+                                         sizeof(INDEX_SCAN_INFO *) *
+                                         (i + test(cpk_scan != NULL)))))
     return TRUE;
 
   uint calc_cost_buff_size=