Description:
------------
I wrote a script to parse a sendmail log file to match records together by message id in order to gather some statistics about a particular relay situation. 

When run, this script quickly swallowed all available RAM, bringing a busy, production system to a standstill.  I reduced the script to the simplest code that causes the memory leak. 

When run as "php -q scriptname.php /var/log/maillog" from the command line, where maillog contains > 500,000 lines, this script will leak memory until the system load average exceeds 5.0. 

Rem out the preg_match on the innermost loop and the memory leak disappears. This bug is found in 4.3.4 and 4.3.6, I haven't tested other versions. 



Reproduce code:
---------------
<?

set_time_limit(0);

// GETS $msgid;
$match="/\]\:\s+([0-9a-zA-Z]+)\:/";

if (!$file=trim($_SERVER['argv'][1]))
        die('You must specify maillog file location');

if ($fp=fopen($file, 'r'))
   {
   while ($line=fgets($fp, 1024))
    if (preg_match($match, $line, $r))
        {
        $msgid=trim($r[1]);
//$mfrom="/$msgid\:\s+from=\<*(.*?)[\s\>].*?relay=.*?\[([0-9\.]+)\]/";
        $mfrom="/$msgid/";

        // REM THIS LINE OUT AND THE MEMORY LEAK STOPS.
        preg_match($mfrom, $line);
        }
   fclose($fp);
   }

?>

Expected result:
----------------
The "top" command should show this PHP instance using < 10% of RAM on a 1 GB RAM system. 

Actual result:
--------------
The "top" command shows > 99% of memory usage on a 1 GB system.