Re: CVE-2023-20593: A use-after-free in AMD Zen2 Processors

["alice" <alice () ayaya dev>]

On Tue Jul 25, 2023 at 1:27 AM UTC, Jonathan Gray wrote:
> On Mon, Jul 24, 2023 at 01:41:36PM -0400, Marc Deslauriers wrote:
> > Hi,
> >
> > There seems to be confusion regarding which is the correct commit:
> >
> > Your blog post says it's 0bc3126c9cfa0b8c761483215c25382f831a7c6f which is
> > for family 17h.
> >
> > This post says it's b250b32ab1d044953af2dc5e790819a7703b7ee6 which is for
> > family 19h.
> >
> > I assume the 17h family one is the correct one?
> >
> > Thanks,
> >
> > Marc.
>
> Yes, but it by no means covers all zen 2 models.  See amd-ucode/README
>
>   Family=0x17 Model=0x31 Stepping=0x00: Patch=0x0830107a Length=3200 bytes
>   Family=0x17 Model=0xa0 Stepping=0x00: Patch=0x08a00008 Length=3200 bytes
>
> 17-31-00 Rome/Castle Peak     0x0830107a
> 17-a0-00 Mendocino            0x08a00008
>
> Models missing include:
>
> 17-60-01 Renoir                       0x0860010b
> 17-68-01 Lucienne             0x08608105
> 17-71-00 Matisse              0x08701032
> 17-90-02 Van Gogh
>
> The known good patch levels are used by xen and linux.  But the
> microcode for Renoir, Lucienne and Matisse is not available as far as
> I can tell.

the amd security bulletin at
https://www.amd.com/en/resources/product-security/bulletin/amd-sb-7008.html
states that really only 2nd-gen epyc is fixed. etas for all other cpus (consumer
level) are in october/november/december.

quoting above:
2nd Gen AMD EPYC™ Processors "Rome" (fixed)
AMD Ryzen 3000 Series Desktop Processors "Matisse" (Target Dec 2023)
AMD Ryzen 4000 Series Desktop Processors with Radeon Graphics "Renoir" AM4 (Target Dec 2023)
AMD Ryzen Threadripper 3000 Series Processors "Castle Peak" HEDT (Target Oct 2023)
AMD Ryzen Threadripper PRO 3000WX Series Processors "Castle Peak" WS SP3 (Target Nov 2023/Dec 2023)
AMD Ryzen 5000 Series Mobile Processors with Radeon Graphics "Lucienne" (Target Dec 2023)
AMD Ryzen 4000 Series Mobile Processors with Radeon Graphics "Renoir" (Target Nov 2023)
AMD Ryzen 7020 Series Processors "Mendocino" FT6 (Target Dec 2023)

this is a disaster of a security announcement from AMD. nothing is fixed except
for epyc. the only workaround anyone really has is the chicken bit, thankfully.