A crash occurred in the odbc_handle_closer function

There is an issue with the order of resource release that needs to be corrected by modifying the code.

• https://github.com/swoole/swoole-src/issues/5956

https://github.com/php/php-src/blob/833120eb72295fd9a6d0cacc68e85cbbeaa6a535/ext/pdo_odbc/odbc_driver.c#L138

The correct code might be:

static void odbc_handle_closer(pdo_dbh_t *dbh) {
    pdo_odbc_db_handle *H = (pdo_odbc_db_handle *) dbh->driver_data;

    SQLFreeHandle(SQL_HANDLE_ENV, H->env);
    H->env = NULL;

    if (H->dbc != SQL_NULL_HANDLE) {
        SQLEndTran(SQL_HANDLE_DBC, H->dbc, SQL_ROLLBACK);
        SQLDisconnect(H->dbc);
        SQLFreeHandle(SQL_HANDLE_DBC, H->dbc);
        H->dbc = NULL;
    }

    pefree(H, dbh->is_persistent);
    dbh->driver_data = NULL;
}

I don't quite understand the logic of the ODBC PDO driver, please review the code above.

==45879== Invalid read of size 8
==45879==    at 0x1185F941: ??? (in /usr/lib/libodbccr.so.2.0.0)
==45879==    by 0x734F411: ??? (in /usr/lib/libodbc.so.2.0.0)
==45879==    by 0x7351182: ??? (in /usr/lib/libodbc.so.2.0.0)
==45879==    by 0x7359691: ??? (in /usr/lib/libodbc.so.2.0.0)
==45879==    by 0x7B01E10: odbc_handle_closer (odbc_driver.c:139)
==45879==    by 0x73F800E: ??? (in /usr/lib/php84/modules/pdo.so)
==45879==    by 0x5CE98E: zend_objects_store_del (in /usr/bin/php84)
==45879==    by 0x586F32: ??? (in /usr/bin/php84)
==45879==    by 0x534247: execute_ex (in /usr/bin/php84)
==45879==    by 0x52D64B: zend_call_function (in /usr/bin/php84)
==45879==    by 0x799996A: swoole::PHPCoroutine::main_func(void*) (swoole_coroutine.cc:773)
==45879==    by 0x7A2B6C7: operator() (std_function.h:591)
==45879==    by 0x7A2B6C7: swoole::coroutine::Context::context_func(transfer_t) (context.cc:149)
==45879==  Address 0x11079928 is 2,344 bytes inside a block of size 5,256 free'd
==45879==    at 0x48B2ECF: free (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==45879==    by 0x73788CA: ??? (in /usr/lib/libodbc.so.2.0.0)
==45879==    by 0x73597E7: ??? (in /usr/lib/libodbc.so.2.0.0)
==45879==    by 0x7B01DFB: odbc_handle_closer (odbc_driver.c:136)
==45879==    by 0x73F800E: ??? (in /usr/lib/php84/modules/pdo.so)
==45879==    by 0x5CE98E: zend_objects_store_del (in /usr/bin/php84)
==45879==    by 0x586F32: ??? (in /usr/bin/php84)
==45879==    by 0x534247: execute_ex (in /usr/bin/php84)
==45879==    by 0x52D64B: zend_call_function (in /usr/bin/php84)
==45879==    by 0x799996A: swoole::PHPCoroutine::main_func(void*) (swoole_coroutine.cc:773)
==45879==    by 0x7A2B6C7: operator() (std_function.h:591)
==45879==    by 0x7A2B6C7: swoole::coroutine::Context::context_func(transfer_t) (context.cc:149)
==45879==    by 0x7B1F70E: swoole_make_fcontext (make_x86_64_sysv_elf_gas.S:135)
==45879==  Block was alloc'd at
==45879==    at 0x48B640A: calloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==45879==    by 0x7378711: ??? (in /usr/lib/libodbc.so.2.0.0)
==45879==    by 0x734A3EE: ??? (in /usr/lib/libodbc.so.2.0.0)
==45879==    by 0x7B022FE: pdo_odbc_handle_factory (odbc_driver.c:498)
==45879==    by 0x73F2A2D: php_pdo_internal_construct_driver (in /usr/lib/php84/modules/pdo.so)
==45879==    by 0x552BD0: ??? (in /usr/bin/php84)
==45879==    by 0x534247: execute_ex (in /usr/bin/php84)
==45879==    by 0x52D64B: zend_call_function (in /usr/bin/php84)
==45879==    by 0x799996A: swoole::PHPCoroutine::main_func(void*) (swoole_coroutine.cc:773)
==45879==    by 0x7A2B6C7: operator() (std_function.h:591)
==45879==    by 0x7A2B6C7: swoole::coroutine::Context::context_func(transfer_t) (context.cc:149)
==45879==    by 0x7B1F70E: swoole_make_fcontext (make_x86_64_sysv_elf_gas.S:135)

ext/pdo_odbc/odbc_driver.c の 136～139 行付近にある odbc_handle_closer から開始し、次に 498 行付近の pdo_odbc_handle_factory と、リンクされている Valgrind トレースを調べます。報告された無効な読み取りに照らしてリソース解放の順序を検証し、報告されたシナリオで解放済みの ODBC 状態にアクセスしなくなっていることを確認します。