Re: [edk2-devel] [PATCH v4] ArmVirt: Allow memory attributes protocol to be disabled

["Ard Biesheuvel" <ardb@kernel.org>]

On Tue, 12 Dec 2023 at 11:08, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> On Tue, Dec 12, 2023 at 09:36:00AM +0100, Ard Biesheuvel wrote:
> > From: Ard Biesheuvel <ardb@kernel.org>
> >
> > Shim's PE loader uses the EFI memory attributes protocol in a way that
> > results in an immediate crash when invoking the loaded image, unless the
> > base and size of its executable segment are both aligned to 4k.
> >
> > If this is not the case, it will strip the memory allocation of its
> > executable permissions, but fail to add them back for the executable
> > region, resulting in non-executable code. Unfortunately, the PE loader
> > does not even bother invoking the protocol in this case (as it notices
> > the misalignment), making it very hard for system firmware to work
> > around this by attempting to infer the intent of the caller.
> >
> > So let's introduce a QEMU command line option to indicate that the
> > protocol should not be exposed at all, and a PCD to set the default for
> > this option when it is omitted.
> >
> >   -fw_cfg opt/org.tianocore/UninstallMemAttrProtocol,string=y
>
> Tested-by: Gerd Hoffmann <kraxel@redhat.com>
> Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
>

Thanks all - I've queued this up now.


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