Re: [Maria-developers] b29ec61724d: MDEV-25906: SIGSEGV in flush_tables_with_read_lock on FTWRL or FTFE | SIGSEGV in ha_maria::extra

Hi, Oleksandr! On Jul 01, Oleksandr Byelkin wrote:

revision-id: b29ec61724d (mariadb-10.6.2-41-gb29ec61724d) parent(s): 83684fc9a4d author: Oleksandr Byelkin committer: Oleksandr Byelkin timestamp: 2021-07-01 11:20:29 +0200 message:

MDEV-25906: SIGSEGV in flush_tables_with_read_lock on FTWRL or FTFE | SIGSEGV in ha_maria::extra

Fixed check of derived tables of all kinds (view, derived, information schema).

diff --git a/sql/sql_reload.cc b/sql/sql_reload.cc index 0fa2fa10df8..e41da9680b0 100644 --- a/sql/sql_reload.cc +++ b/sql/sql_reload.cc @@ -592,10 +592,19 @@ bool flush_tables_with_read_lock(THD *thd, TABLE_LIST *all_tables) for (TABLE_LIST *table_list= all_tables; table_list; table_list= table_list->next_global) { - if (!(table_list->is_view() || - table_list->table->file->ha_table_flags() & HA_CAN_EXPORT)) + /* + We allow all deriveds and view here, but prohibit information_schema + tables (explicitly) and performance_schema tables (implicetly: + engine do not suport export) + */ + if (table_list->is_non_derived() && + (!table_list->is_base_table() || + !(table_list->table->file->ha_table_flags() & HA_CAN_EXPORT))) { - my_error(ER_ILLEGAL_HA, MYF(0),table_list->table->file->table_type(), + my_error(ER_ILLEGAL_HA, MYF(0), + (table_list->is_base_table() ? + table_list->table->file->table_type(): + "information_schema"),

I'd say if you want to detect I_S tables, you should test for table_list->schema_table. It's not clear what your condition actually does. And there is no such engine "information_schema", so the message is misleading. In fact, this should be access denied. For both. Like: mysqltest: At line 12: query 'flush table information_schema.collations for export' failed: ER_DBACCESS_DENIED_ERROR (1044): Access denied for user 'foo'@'localhost' to database 'information_schema' this is from a test file that only does flush table information_schema.collations for export.

table_list->db.str, table_list->table_name.str); goto error_reset_bits; } @@ -607,7 +616,8 @@ bool flush_tables_with_read_lock(THD *thd, TABLE_LIST *all_tables) for (auto table_list= all_tables; table_list; table_list= table_list->next_global) { - if (!table_list->is_view() && + if (table_list->table &&

why do you check for table_list->table ? Can it happen that table_list->table == NULL and table_list->is_base_table() == true?

+ table_list->is_base_table() && table_list->table->file->extra(HA_EXTRA_FLUSH)) goto error_reset_bits; }

Regards, Sergei VP of MariaDB Server Engineering and security@mariadb.org