Re: CVE-2024-35802: x86/sev: Fix position dependent variable references in startup code

[Nikolay Borisov]

On 23.05.24 г. 15:17 ч., Greg Kroah-Hartman wrote:
> On Thu, May 23, 2024 at 03:01:56PM +0300, Nikolay Borisov wrote:
> > On 23.05.24 г. 14:21 ч., Greg Kroah-Hartman wrote:
> > > Isn't crashing SEV guests a problem with "availability"?  That term
> > > comes from the CVE definition of what we need to mark as a CVE, which is
> > > why this one was picked.
> >
> > But availability has never been one of the tenets of CoCo, in fact in
> > sev-snp/tdx the VMM is explicitly considered outside of the TCB so
> > availability cannot be guaranteed.
>
> This has nothing to do with CoCo (but really, ability of the host to
> crash the guest seems like it should be as I would assume that CoCo
> guests would want to be able to be run...)
>
> Official CVE definition of vulnerability from cve.org:
> 	An instance of one or more weaknesses in a Product that can be
> 	exploited, causing a negative impact to confidentiality, integrity, or

I don't see how this is exactly "explotaible" i.e if a guest is run and 
it crashes during bootup it simply won't run. Can this be considered 
active exploitation of an issue?

> 	availability; a set of conditions or behaviors that allows the
> 	violation of an explicit or implicit security policy.
>
> I think "able to crash SEV guests" is a direct weakness that has to do
> with availability here which is why I marked it as such (as did other
> reviewers.)  Now if CoCo wants to claim it as part of their security
> implicit or explicit security policy, all the better :)
>
> thanks,
>
> greg k-h