MDEV-16552: [10.0] ASAN global-buffer-overflow in is_stat_table / statistics_for_tables_is_needed

Backport the fix f214d365 to 10.0

   Author: Sergei Golubchik <serg@mariadb.org>
   Date:   Tue Apr 17 00:44:34 2018 +0200

    ASAN error in is_stat_table()

    don't memcmp beyond the first argument's end

    Also: use my_strcasecmp(table_alias_charset), like elsewhere, not memcmp

mysql-test/r/stat_tables.result

@@ -516,4 +516,11 @@ use test;
 drop database db1;
 drop database db2;
 drop table t1;
+#
+# MDEV-16552: [10.0] ASAN global-buffer-overflow in is_stat_table / statistics_for_tables_is_needed
+#
+SET use_stat_tables = PREFERABLY;
+SELECT CONVERT_TZ( '1991-09-20 10:11:02', '+00:00', 'GMT' );
+CONVERT_TZ( '1991-09-20 10:11:02', '+00:00', 'GMT' )
+NULL
 set use_stat_tables=@save_use_stat_tables;

mysql-test/r/stat_tables_innodb.result

@@ -543,6 +543,13 @@ use test;
 drop database db1;
 drop database db2;
 drop table t1;
+#
+# MDEV-16552: [10.0] ASAN global-buffer-overflow in is_stat_table / statistics_for_tables_is_needed
+#
+SET use_stat_tables = PREFERABLY;
+SELECT CONVERT_TZ( '1991-09-20 10:11:02', '+00:00', 'GMT' );
+CONVERT_TZ( '1991-09-20 10:11:02', '+00:00', 'GMT' )
+NULL
 set use_stat_tables=@save_use_stat_tables;
 set optimizer_switch=@save_optimizer_switch_for_stat_tables_test;
 SET SESSION STORAGE_ENGINE=DEFAULT;

mysql-test/t/stat_tables.test

@@ -305,4 +305,10 @@ drop database db1;
 drop database db2;
 drop table t1;
 
+--echo #
+--echo # MDEV-16552: [10.0] ASAN global-buffer-overflow in is_stat_table / statistics_for_tables_is_needed
+--echo #
+
+SET use_stat_tables = PREFERABLY;
+SELECT CONVERT_TZ( '1991-09-20 10:11:02', '+00:00', 'GMT' );
 set use_stat_tables=@save_use_stat_tables;

sql/sql_statistics.cc

@@ -3858,11 +3858,11 @@ bool is_stat_table(const char *db, const char *table)
 {
   DBUG_ASSERT(db && table);
 
-  if (!memcmp(db, stat_tables_db_name.str, stat_tables_db_name.length))
+  if (!my_strcasecmp(table_alias_charset, db, stat_tables_db_name.str))
   {
     for (uint i= 0; i < STATISTICS_TABLES; i ++)
     {
-      if (!memcmp(table, stat_table_name[i].str, stat_table_name[i].length))
+      if (!my_strcasecmp(table_alias_charset, table, stat_table_name[i].str))
         return true;
     }
   }