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| Subject: | [Full-disclosure] Re: Java integer overflows (was: a really long topic) |
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| Date: | Wed, 29 Mar 2006 10:41:29 +0100 |
Hello, Even though java throws an exception if a catch is not present the thread is killed. The code that threw the exception is never resumed. Also using a finally block can ensure things stop gracefully. Developers (I used to be one) also catch exceptions and bury them by not doing anything with them. -ek On 29/03/06, Andrew van der Stock <vanderaj@greebo.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@gmail.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@greebo.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
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