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

[Greg Kroah-Hartman]

On Thu, May 23, 2024 at 03:21:05PM +0300, Nikolay Borisov wrote:
> 
> 
> 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?

Isn't preventing a guest from running something that causes a lack of
avaiability?  Again, that's why we picked this commit, it keeps the
system from working properly as expected.

thanks,

greg k-h