Re: [PATCH v9 02/29] x86/boot: Relocate definition of the initial state of CR0

Ricardo Neri
2017-10-27T19:03:32Z

On Thu, Oct 26, 2017 at 02:55:13PM +0200, Borislav Petkov wrote:
> On Thu, Oct 26, 2017 at 02:02:02AM -0700, Andy Lutomirski wrote:
> > I'm assuming that UMIP_REPORTED_CR0 will never change. If CR0 gets a
> > new field that we set some day, then I assume that CR0_STATE would add
> > that bit but UMIP_REPORTED_CR0 would not.
>
> Yeah, let's do that when it is actually needed.

Thanks Andy! I reasoned that for UMIP could report CR0_STATE a value that
is already revealed in the source code. Thus, if CR0 ever changes at run
time, an attacker could only see what is set programmatically.

BR,

Ricardo