Buffer overflow in dict_index_t::col_info::add()

diff --git a/mysql-test/suite/innodb/t/innodb-index-online.test b/mysql-test/suite/innodb/t/innodb-index-online.test

index 2cb84b18402..2f5926d3a53 100644

--- a/mysql-test/suite/innodb/t/innodb-index-online.test

+++ b/mysql-test/suite/innodb/t/innodb-index-online.test

@@ -15,7 +15,8 @@ SET GLOBAL innodb_file_per_table = on;

 # Save the initial number of concurrent sessions.

 --source include/count_sessions.inc

-CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 INT, c3 TEXT)

+CREATE TABLE t1 (c1 INT PRIMARY KEY, c2 INT,

+c3 VARCHAR(10) CHARACTER SET utf8 COLLATE utf8_bin, INDEX c2c3(c2,c3))

 ENGINE=InnoDB STATS_PERSISTENT=0;

 INSERT INTO t1 VALUES (1,1,''), (2,2,''), (3,3,''), (4,4,''), (5,5,'');

@@ -377,10 +378,11 @@ CHECK TABLE t1;

 --error ER_DUP_ENTRY

 ALTER TABLE t1 ADD UNIQUE INDEX c3p5(c3(5));

 UPDATE t1 SET c3 = NULL WHERE c3 = '';

+ALTER TABLE t1 ADD UNIQUE INDEX c3p5(c3(5));

 SET lock_wait_timeout = 1;

 SET DEBUG_SYNC = 'row_log_apply_before SIGNAL c3p5_created WAIT_FOR ins_done';

 --send

-ALTER TABLE t1 ADD UNIQUE INDEX c3p5(c3(5));

+ALTER TABLE t1 MODIFY c3 VARCHAR(10) CHARACTER SET utf8 COLLATE utf8_unicode_ci;

 connection default;

 SET DEBUG_SYNC = 'now WAIT_FOR c3p5_created';

CURRENT_TEST: innodb.innodb-index-online

mysqltest: At line 401: query 'reap' failed with wrong errno <Unknown> (2013): 'Lost connection to server during query', instead of ER_LOCK_WAIT_TIMEOUT (1205)...

…

mariadbd: /mariadb/10.6/storage/innobase/include/dict0mem.h:980: dict_col_t* dict_index_t::col_info::add(mem_heap_t*, const dict_col_t&, unsigned int): Assertion `offset < n_cols' failed.