Re: Intel microcode fixes [OFF-TOPIC]

David Woodhouse (David.Woodhouse@mvhi.com)
Fri, 20 Nov 1998 17:38:12 +0000

jfulmer@appin.ml.org said:
> In a serious note (microcode viruses aside), I don't think that I or
> many other people even knew that Intel's microcode was changeable. I
> wonder what the security implications could be?

> Does Linux protect the cpu at all in this instance?

Speaking purely from conjecture, I'd assume that you have to be in ring 0 to
change the microcode, and ISTR you might even have to do it while booting -
before ever switching to protected mode.

So at the worst, you have to be root (and use iopl()) to do it. I don't think
we need to worry too much.

---- ---- ----
David Woodhouse David.Woodhouse@mvhi.com Office: (+44) 1223 810302
Project Leader, Process Information Systems Mobile: (+44) 976 658355
Axiom (Cambridge) Ltd., Swaffham Bulbeck, Cambridge, CB5 0NA, UK.
finger dwmw2@ferret.lmh.ox.ac.uk for PGP key.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/