Description:
------------
A segfault has existed in PHP since at least 5.2.17 when using ODBC with SQL Server Native Client driver.

Selecting NULL values in a computed expression causes the segfault.

I created a patch for this over a year ago and submitted the pull request here: https://github.com/php/php-src/pull/193

The pull request has not been accepted, so the segfault still exists even in 5.5.0beta2.



Test script:
---------------
<?php

$conn = odbc_connect('Driver=SQL Server Native Client 11.0;server=xxx;uid=xxx;pwd=xxx;Database=xxx','','');

$query = odbc_exec($conn, 'select null');

$segfault = odbc_fetch_array($query); // segfault



Expected result:
----------------
odbc_fetch_array to return a result rather than segfault.

Actual result:
--------------
segfault.