Impact

The following code: https://github.com/php/php-src/blob/5070fbf1613015e351bc4629ac7997b26359320b/ext/pdo_firebird/firebird_driver.c#L805-L808

and the following code: https://github.com/php/php-src/blob/c34b37fe0b5c099fcf506c5400552d6bbb95cd79/ext/pdo_dblib/dblib_driver.c#L164-L174

Can cause integer overflow, or can become a value over ZSTR_MAX_LEN causing an overflow, which eventually turns into an OOB write. This is triggerable on 32-bit especially.