linux-kernel - Re: [PATCH] regmap: Fix the null function of format_val on regmap_bulk

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Date:	Wed, 26 Aug 2015 18:38:12 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Markus Pargmann <mpa@...gutronix.de>
Cc:	Henry Chen <henryc.chen@...iatek.com>,
	linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
	Sascha Hauer <kernel@...gutronix.de>,
	Matthias Brugger <matthias.bgg@...il.com>,
	eddie.huang@...iatek.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] regmap: Fix the null function of format_val on
 regmap_bulk_read.

On Wed, Aug 26, 2015 at 03:22:46PM +0200, Markus Pargmann wrote:
> On Wed, Aug 26, 2015 at 01:35:56PM +0100, Mark Brown wrote:
> > On Wed, Aug 26, 2015 at 07:43:16PM +0800, Henry Chen wrote:

> > Why are these format functions sensible?  Converting a null pointer
> > dereference into data corruption wouldn't be ideal.  The commit message
> > should really cover this.

> The regmap_bulk_read() function worked before the following patch:
> 	15b8d2c41fe5 (regmap: Fix regmap_bulk_read in BE mode)

Define "worked" here.

> As far as I can see this patch fixes this issue by using simple format
> functions. Before the above mentioned patch, the code used memcpy. Now
> regmap_format_*_native is used which should result in the same behaviour
> but fixes the null pointer.

Again, this sort of analysis needs to be in the commit message (and
really ought to explain why the resulting API makes sense).

> I am not sure if there are other locations in the code where format_val
> is used in this setup so I don't know if this would change behavior in a
> different codepath.

Which is another part of the concern, being able to format values is a
more general concept.

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