[LINK] Microsoft explains how the ANI bug got baked into Vista

[Bernard Robertson-Dunn]

Adrian Chadd wrote:

> On Mon, Apr 30, 2007, Bernard Robertson-Dunn wrote:
> 
>><brd>
>>When I used to do assembly programming on Univac mainframes in the mid 
>>1970s, they had a concept of privileged Operating System mode. This 
>>meant that the Operating System had its own set of registers and some OS 
>>only instructions. The consequences of this were two fold:
> 
> 
> Current Intel CPU architecture has that too. In fact, it has -four-
> protection rings to seperate privileged and non-priviliged processes.
> The whole point of having protected mode is being able to setup a process
> in its own "virtual machine" with limited interfaces to the rest of
> the system.

I didn't think that the Intel architecture had a set of registers that 
only the OS could use.  I thought that all registers were used by both 
OS and application code, which is why buffer overflow hacks are possible.

In the Univac architecture, there was no such thing as a buffer overflow 
hack in the sense of application data being executed as either 
application code or OS code.

-- 

Regards
brd

Bernard Robertson-Dunn
Sydney Australia
brd at iimetro.com.au