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TUCoPS :: Web :: Apps :: bt1337.txt

Java 1.4.2_02 InsecurityManager JVM crash JAV:





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Hello,

 Java 2 Security Managers are objects that should enforce
 system integrity and safety. Everyone would expect that
 the provided base classes from the JDK are therefore a
 role model for code quality and stability. But that's
 all theory. Let's do some practice:

 Imagine a lazy implementor (like me) of a SecurityManager,
 he codes the following:

 /* InsecurityManager-Demonstration  */
 /* coded by Marc Schoenefeld        */
 public class InSecurityManager extends SecurityManager {

       public void doit() {
       =09          System.out.println("doit");
       =09=09  int o =3D classDepth(null);
       }

   public static void main(String[] a) {
   =09InSecurityManager m =3D  new InSecurityManager();
   =09m.doit();
   }
}
 When you run the class with the command

 java InSecurityManager

 you get a jvm crash, instead of  a null pointer exception.
 I tested this with the latest 1.3.1,1.4.1,1.4.2 implementations.
 All Sun implementations crash, the IBM 1.4.1 (comes with
 Websphere or Cloudscape) is stable.

 This sample of code will do no harm to productive environments,
 because you cannot instantiate a second security manager, but
 it may be a snapshot of the inner condition of jvm security.

 Lesson learned: Do not believe white papers or specifications,
 test the implementation and report bugs to the vendor. Choose
 a stable implementation.

 Sincerely
 Marc Schoenefeld


- --

Never be afraid to try something new. Remember, amateurs built the
ark; professionals built the Titanic. -- Anonymous

Marc Sch=F6nefeld Dipl. Wirtsch.-Inf. / Software Developer

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