Mail Archives: djgpp/1997/03/10/05:39:43
"John M. Aldrich" (fighteer AT cs DOT com) writes:
> Paul Derbyshire wrote:
>>
>> As for a ring 3 program being unable to currupt the kernel, I'm not sure
>> this is entirely correct. I discovered that a DOS program running in a DOS
>> box under Win 95 (and DOS boxes presumably run in ring 3) can crash the
>> machine with a bad memory write.
>
> All DOS programs are not DPMI programs. Real-mode code that runs in a
> DOS box will completely ignore the memory manager and can go ahead and
> corrupt anything it likes. Usually, Win95 will catch the program at it,
> but it can still take down your computer.
Flame me if I'm wrong, but doesn't a DOS box run on a virtual machine with
its own Windows-provided image of the real memory map? Aren't all of its
transactions indirect via the Windows kernel then?
[DOS is terribly insecure]
Is this caused by an aspect of Intel CPU design or by an aspect of the
DPMI spec?
--
.*. Where feelings are concerned, answers are rarely simple [GeneDeWeese]
-() < When I go to the theater, I always go straight to the "bag and mix"
`*' bulk candy section...because variety is the spice of life... [me]
Paul Derbyshire ao950 AT freenet DOT carleton DOT ca, http://chat.carleton.ca/~pderbysh
- Raw text -