Re: [PATCH] Enable reset attack mitigation

From	Matthew Garrett <mjg59@google.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] Enable reset attack mitigation
Date	2017-08-05 23:50 +0200
Message-ID	<ubf7k-1Vj-13@gated-at.bofh.it> (permalink)
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On Sat, Aug 5, 2017 at 10:34 AM, Lukas Wunner <lukas@wunner.de> wrote:
> Just an innocent question from a bystander, what's the downside of
> unconditionally requesting that memory be overwritten?  Does it
> prolong reboot noticeably?

Yes, it's just to avoid stalling reboot for as long as it takes to clear RAM.

> I've also wondered why you've chosen to put this in a separate file
> rather than the existing secureboot.c, my naive understanding is that
> TPM and SecureBoot is related but I'm not an expert on this.  It would
> allow you to reuse the existing get_efi_var() macro.

It's not related to Secure Boot (systems can have TPMs but not Secure
Boot, and vice versa), the spec is managed by a different body (TCG
rather than UEFI), and there'll be more TPM-related code for the boot
stub in future.

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[PATCH] Enable reset attack mitigation Matthew Garrett <mjg59@google.com> - 2017-08-04 23:30 +0200
  Re: [PATCH] Enable reset attack mitigation Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-08-05 12:00 +0200
    Re: [PATCH] Enable reset attack mitigation Matthew Garrett <mjg59@google.com> - 2017-08-05 18:40 +0200
      Re: [PATCH] Enable reset attack mitigation Lukas Wunner <lukas@wunner.de> - 2017-08-05 19:40 +0200
        Re: [PATCH] Enable reset attack mitigation Matthew Garrett <mjg59@google.com> - 2017-08-05 23:50 +0200

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