Description:
------------
Crypt() SHA256 and SHA512 segfault when passed a salt that contains a null byte. 
This is because the emalloc call and the memset call use different length inputs 
for the `output` string.  The memset call then overflows the buffer.

Test script:
---------------
<?php
crypt("foo", '$5$'.chr(0).'abc');
?>

and

<?php
crypt("foo", '$6$'.chr(0).'abc');
?>

Expected result:
----------------
No output

Actual result:
--------------
Either segmentation fault (sha512) or zend_mm_heap corrupted (sha256)