Date: Mon, 24 Jul 2017 14:34:10 +0100
From: Matt Fleming <matt@codeblueprint.co.uk>
To: Baoquan He <bhe@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>, linux-kernel@vger.kernel.org,
        x86@kernel.org, keescook@chromium.org, tglx@linutronix.de,
        hpa@zytor.com, izumi.taku@jp.fujitsu.com, fanc.fnst@cn.fujitsu.com,
        thgarnie@google.com, n-horiguchi@ah.jp.nec.com
Subject: Re: [PATCH v6 RESEND] x86/boot/KASLR: Restrict kernel to be
 randomized in mirror regions
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 <20170721131956.GK2344@x1>
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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.