Re: How to develop a random number generation device

On Sep 12, 9:26 pm, JosephKK <joseph_barr...@xxxxxxxxxxxxx> wrote:
John Larkin jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx posted to
sci.electronics.design:



On Tue, 11 Sep 2007 17:28:32 +0100, Nobody <nob...@xxxxxxxxxxx>
wrote:

On Tue, 11 Sep 2007 07:44:01 -0700, John Larkin wrote:

Cool. When can we expect buffer overrun exploits to be impossible
under Windows?

When it stops letting you run arbitrary machine code.

Nothing the OS does can prevent machine code from overrunning a
buffer.

Ancient computers, PDP-11 and VAX certainly, had memory management
hardware that separated I and D space, where I space was read-only,
and D space could not be executed. And the OS's enforced those
rules. It was common to have many users running the exact same code,
but mapped into different data spaces.

Problem is, neither Intel nor Microsoft was in the mainstream of
computing when they kluged up x86 and Windows.

John

The hardware only became capable of the basics of worthwhile
implementation in early Pentiums, and became capable of really
worthwhile implementations with Opteron (AMD) and EMT64 (Intel).


I disagree with what you may not have meant to say above. In the
microprocessor area, you are largely correct but in other machines,
there were many hardware systems that could protect against buffer
overflows getting evil code to run. Some of them used a different
stack for call and return than for the data. Some such as the IBM-360
didn't have a stack and required each routine to handle its "save
area".

Some of the more DSPish machines would also be hard to make a buffers
overflow do anything evil. They are far from general purpose machines
so although they may show that it could have been done, we can say
that they could have made a general purpose PC that was well defended.






.

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