linux-kernel - Re: [PATCH 2/2] pci: Update VPD size with correct length

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Date:	Fri, 18 Dec 2015 14:57:39 +0100
From:	Hannes Reinecke <hare@...e.de>
To:	Alexander Duyck <alexander.duyck@...il.com>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Michal Kubecek <mkubecek@...e.com>,
	"Shane M. Seymour" <shane.seymour@....com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Bjorn Helgaas <helgaas@...nel.org>
Subject: Re: [PATCH 2/2] pci: Update VPD size with correct length

On 12/18/2015 02:49 PM, Alexander Duyck wrote:
> On Fri, Dec 18, 2015 at 12:35 AM, Hannes Reinecke <hare@...e.de> wrote:
>> PCI-2.2 VPD entries have a maximum size of 32k, but might actually
>> be smaller than that. To figure out the actual size one has to read
>> the VPD area until the 'end marker' is reached.
>> Trying to read VPD data beyond that marker results in 'interesting'
>> effects, from simple read errors to crashing the card. And to make
>> matters worse not every PCI card implements this properly, leaving
>> us with no 'end' marker or even completely invalid data.
>> This path modifies the size of the VPD attribute to the available
>> size, or set it to '0' if no valid data could be read.
>
> This isn't what I had in mind.  There is no need to add an f0 version
> of the size function.  The size for all functions other than function
> 0 when the F0 flag is set is 0.  We aren't going to be reading their
> VPD, we only read the VPD region of function 0.
>
Ah. (I'm a bit confused about the proposed action for VPD other than 
function 0).
So the idea here is to _disallow_ access to VPDs from functions 
other than '0' unless these functions have different PCI IDs?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@...e.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
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