Re: How to develop a random number generation device

On Mon, 17 Sep 2007 23:37:49 +0100, Nobody wrote:
On Sat, 15 Sep 2007 17:06:31 +0000, Rich Grise wrote:

That doesn't address the issue, which was whether the OS can
prevent buffer overruns.

With a hardware MMU, and software that can catch the exception, yes.

That still doesn't address the question of how you decide that a write
operation has overrun its buffer; the details of where one buffer starts
and another ends are unknown to the OS.

But it knows what chunks of memory it has allocated to a particular
process. As long as it's in your own memory space, who cares if you
overwrite/overrun your own buffers?

Doing so is the essence of a "buffer overrun exploit", one of the most
common types of security vulnerability for code written in C/C++.

It allows a malicious user to make a program do something that it isn't
supposed to do.

E.g. consider a program being run on a web server to process form
input from a web page. If the program suffers from a buffer overrun flaw,
simply sending the right data in a POST request can allow the attacker to
execute arbitrary code on the web server.

My God! You've got to quit using MICRO$~1 web servers!

Good Luck!
Rich

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