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SubjectRe: [PATCH v6 RESEND] x86/boot/KASLR: Restrict kernel to be randomized in mirror regions

* Matt Fleming <matt@codeblueprint.co.uk> wrote:

> On Fri, 21 Jul, at 09:19:56PM, Baoquan He wrote:
> >
> > There are places where the efi map is getting and used like this. E.g
> > in efi_high_alloc() of drivers/firmware/efi/libstub/efi-stub-helper.c.
> > EFI developers worry the size of efi_memory_desc_t could not be the same
> > as e->efi_memdesc_size?
> >
> > Hi Matt,
> >
> > Could you help have a look at this?
>
> You're exactly right. The code guards against the size of the
> efi_memory_desc_t struct changing. The UEFI spec says to traverse the
> memory map this way.

This is not obvious and looks pretty ugly as well, and open coded in several
places.

At minimum we should have an efi_memdesc_ptr(efi, i) wrapper inline (or so) that
gives us the entry pointer, plus a comment that points out that ->memdesc_size
might not be equal to sizeof(efi_memory_memdesc_t).

Thanks,

Ingo

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