linux-kernel - Re: [PATCH] x86/efistub: Omit physical KASLR when memory reservations exist

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Message-ID: <202405161142.A62A23A9@keescook>
Date: Thu, 16 May 2024 11:45:03 -0700
From: Kees Cook <keescook@...omium.org>
To: "Chaney, Ben" <bchaney@...mai.com>
Cc: Ard Biesheuvel <ardb+git@...gle.com>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>, Ard Biesheuvel <ardb@...nel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH] x86/efistub: Omit physical KASLR when memory
 reservations exist

On Thu, May 16, 2024 at 05:29:11PM +0000, Chaney, Ben wrote:
> > +static efi_status_t parse_options(const char *cmdline)
> > +{
> > + static const char opts[][14] = {
> > + "mem=", "memmap=", "efi_fake_mem=", "hugepages="
> > + };
> > +
> 
> I think we probably want to include both crashkernel and pstore as arguments that can disable this randomization.

The carve-outs that pstore uses should already appear in the physical
memory mapping that EFI has. (i.e. those things get listed in e820 as
non-RAM, etc)

I don't know anything about crashkernel, but if we really do have a lot
of these, we likely need to find a way to express them to EFI...

-- 
Kees Cook