This code causes a segfault both on Linux and Win32 builds.

<?php

function utf8IsValidString($AStr)
{
  $ptrASCII  = '[\x00-\x7F]';
  $ptr2Octet = '[\xC2-\xDF][\x80-\xBF]';
  $ptr3Octet = '[\xE0-\xEF][\x80-\xBF]{2}';
  $ptr4Octet = '[\xF0-\xF4][\x80-\xBF]{3}';
  $ptr5Octet = '[\xF8-\xFB][\x80-\xBF]{4}';
  $ptr6Octet = '[\xFC-\xFD][\x80-\xBF]{5}';

  return preg_match("/^($ptrASCII|$ptr2Octet|$ptr3Octet|$ptr4Octet|$ptr5Octet|$ptr6Octet)*$/s", $AStr);
}

// read text
$handle = fopen('utf8text.txt', 'r');
$stat = fstat($handle);
$str = fread($handle, $stat['size']);
fclose($handle);

// execute PCRE match
var_dump(utf8IsValidString("some short text \xC4\xBE\xC5\xA1")); // ok
var_dump(utf8IsValidString($str));                               // segfault

?>

This code including data file to reproduce bug can be found here: http://www.omikron.sk/downloads/pcre_crash.tar