On a 32-bit system and Symfony 2.3:

Since Improve bytes conversion method was merged #7413, the getPostMaxSize function in Symfony\Component\Form\Extension\Validator\Util\ServerParams.php returns a bad int number (whether the iniMax number is greater than PHP_INT_MAX 2147483647).

The error comes from the line 36:

return intval($match[2], $bases[$match[1]]) << $shifts[$match[3]];

For instance '2G' gives:

return 2 << 30;  // -2147483648 

Indeed, the Shift left operator on PHP does a bitwise operation (and so returns an integer instead of a double : needed here )

It is really damaging since all Symfony2 forms use this verification when posting data.