Re: Xen Security Advisory 407 v1 (CVE-2022-23816,CVE-2022-23825,CVE-2022-29900) - Retbleed - arbitrary speculative code execution with return instructions

[Andrew Cooper <Andrew.Cooper3 () citrix com>]

On 12/07/2022 20:34, Salvatore Bonaccorso wrote:
> Hi,
>
> On Tue, Jul 12, 2022 at 09:27:07PM +0200, Salvatore Bonaccorso wrote:
> > Hi,
> >
> > On Tue, Jul 12, 2022 at 04:36:10PM +0000, Xen.org security team wrote:
> > > -----BEGIN PGP SIGNED MESSAGE-----
> > > Hash: SHA256
> > >
> > >  Xen Security Advisory CVE-2022-23816,CVE-2022-23825,CVE-2022-29900 / XSA-407
> > >
> > >    Retbleed - arbitrary speculative code execution with return instructions
> > >
> > > ISSUE DESCRIPTION
> > > =================
> > >
> > > Researchers at ETH Zurich have discovered Retbleed, allowing for
> > > arbitrary speculative execution in a victim context.
> > >
> > > For more details, see:
> > >   https://comsec.ethz.ch/retbleed
> > >
> > > ETH Zurich have allocated CVE-2022-29900 for AMD and CVE-2022-29901 for
> > > Intel.
> > >
> > > Despite the similar preconditions, these are very different
> > > microarchitectural behaviours between vendors.
> > >
> > > On AMD CPUs, Retbleed is one specific instance of a more general
> > > microarchitectural behaviour called Branch Type Confusion.  AMD have
> > > assigned CVE-2022-23816 (Retbleed) and CVE-2022-23825 (Branch Type
> > > Confusion).
> > >
> > > For more details, see:
> > >   https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1037
> > Is it confirmed that AMD is not using CVE-2022-29900? The above
> > amd-sb-1037 references as well both CVE-2022-23825 (Branch Type
> > Confusion) and CVE-2022-29900 (RETbleed), so I assume they agreed to
> > use CVE-2022-29900 for retbleed?
> >
> > So should the Xen advisory as well use CVE-2022-23825,CVE-2022-29900
> > and CVE-2022-29901?
> Nevermind, I missunderstood the wording and the advisory just mentions
> all the related CVEs correctly and made a thinko. It might turn out
> that CVE-2022-23816 will not be used, but then the title would read
> only as 
>
> Xen Security Advisory CVE-2022-23825,CVE-2022-29900 / XSA-407
>
> So please disregard the question above.

/sigh

AMD changed the CVE in the bulletin between the final draft, and what
went public.

CVE-2022-23816 has been referenced by multiple other vendors too, so is
definitely out in the world.  Hopefully MITRE will close out one of
CVE-2022-23816 and CVE-2022-29900 as a dup of the other.

For now, I think the least confusing option is to keep both referenced.

~Andrew