From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
Subject: Re: [PATCH v2 1/2] efi/capsule: Add 'capsule' lookup support
Date: Thu, 2 Mar 2017 16:44:02 +0000
Message-ID: <20170302164402.GB9522@codeblueprint.co.uk>
References: <20170301175943.87444-1-qiuxu.zhuo@intel.com>
 <20170301175943.87444-2-qiuxu.zhuo@intel.com>
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To: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: Qiuxu Zhuo <qiuxu.zhuo-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, "linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Tony Luck <tony.luck-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
List-Id: linux-efi@vger.kernel.org

On Thu, 02 Mar, at 03:38:51PM, Ard Biesheuvel wrote:
> 
> > +       if (!capsule)
> > +               return -ENOMEM;
> > +
> > +       capsule += sizeof(uint32_t);
> 
> This is incorrect for 64-bit. You need to increment by the size of
> unsigned long here, regardless of the size of efi_capsule_num.

I'm almost positive this is correct, but I can't find the bit in the
spec that says why. We're not trying to step over a pointer here, if
memory serves, it's a capsule count or something and uint32_t is the
right type.

Lemme go dig in the spec.