full-disclosure - Java integer overflows (was: a really long topic)

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Date: Wed Mar 29 19:43:15 2006
From: thorpflyer at yahoo.com (Simon Roberts)
Subject: Java integer overflows (was: a really long
	topic)

Seems to me that such ranges are application specific and therefore
your problem, not the JVMs. You're describing a bug in your code, due
to failure to validate, not a bug in the JVM which behaves exactly (and
quite possibly provably) according to its specification.

--- Andrew van der Stock <vanderaj@...ebo.net> wrote:

> I'm not talking arbitrary code execution, I'm talking about odd code 
> 
> paths, bizarre outcomes, and DoS.
> 
> For example (found via 19 Sins, Viega, Howard and LeBlanc):
> http://seclists.org/lists/bugtraq/2004/Nov/0097.html
> 
> I know Michael reads webappsec, he may have more examples.
> 
> In my own code testing, I look for silly behaviors if a user can  
> insert a large or negative number. You'd be surprised how often it  
> occurs. There is no excuse not to include basic range checks when  
> performing data validation.
> 
> thanks,
> Andrew
> 
> On 29/03/2006, at 2:30 PM, michaelslists@...il.com wrote:
> 
> > No you dont.
> >
> > Arrays are all bounds checked; ..., that is, the following code
> will
> > throw an exception:
> >
> > ================================
> > class Foo {
> >   static {
> >     int[] m = new int[2];
> >     System.out.println(m[34]);
> >   }
> > }
> > ================================
> >
> >
> > What do you mean by "overflow"? Do you mean this?
> >
> > ================================
> > class Foo {
> >   static {
> >     int m = Integer.MAX_VALUE;
> >     int k = Integer.MAX_VALUE + Integer.MAX_VALUE;
> >     System.out.println(m);
> >     System.out.println(k);
> >     System.exit(0);
> >   }
> > }
> > ================================
> >
> > if so, I don't see how that is an issue.
> >
> > -- Michael
> >
> >
> >
> > On 3/29/06, Andrew van der Stock <vanderaj@...ebo.net> wrote:
> >> This is not quite true.
> >>
> >> Java does not prevent integer overflows (it will not throw an
> >> exception). So you still have to be careful about array indexes.
> >>
> >> Andrew
> 
> > _______________________________________________
> Full-Disclosure - We believe in it.
> Charter: http://lists.grok.org.uk/full-disclosure-charter.html
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"You can tell whether a man is clever by his answers. You can tell whether a man is wise by his questions." ? Naguib Mahfouz

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