Messages in this thread | | | Date | Fri, 8 Aug 2014 17:21:35 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH 7/8] x86, microcode, intel: forbid some incorrect metadata |
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On Fri, Aug 08, 2014 at 10:50:57AM -0300, Henrique de Moraes Holschuh wrote: > On Fri, 08 Aug 2014, Borislav Petkov wrote: > > If someone tries to load a microcode blob which has been split and so > > on, then we should refuse loading. We want to accept microcode from the > > vendor and nothing else glued together. > > I don't quite get why we should refuse microcode
Because the blob from the official location passes internal validation, I'd strongly assume. Everything else doesn't.
> that has been split by userspace when the Intel SDM explicitly states > that tools can do that if there is a need,
Where?
> In these last two weeks I tried to look around for microcode loader > implementantions, and now I believe we will *never* see microcode with the > current version of the extended signatures specification. The loaders in > the field are just too broken, Intel might as well come up with a new and > enhanced design that doesn't have so many sharp edges, since nearly everyone > will have to patch their loaders anyway.
You can't just assume that just because implementations are faulty there - they should adhere to the SDM and it is authoritative. If the extended signatures are really needed at some point, implementations will have to be fixed.
> I will respin the patch without the %1024 comment. Note that I never > *removed* any test, we never tested for %1024 in the first place
And I'm saying we should if we're loading the official blob.
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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