linux-kernel - Re: [PATCH] i2c: busses: i2c-pxa.c: Fix for possible null pointer dereference

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Message-id: <004801cf7e05$c3354c20$499fe460$%han@samsung.com>
Date:	Mon, 02 Jun 2014 10:55:43 +0900
From:	Jingoo Han <jg1.han@...sung.com>
To:	'Rickard Strandqvist' <rickard_strandqvist@...ctrumdigital.se>,
	'Wolfram Sang' <wsa@...-dreams.de>
Cc:	'Grant Likely' <grant.likely@...aro.org>,
	'Rob Herring' <robh+dt@...nel.org>,
	'Leilei Shang' <shangll@...vell.com>,
	'Daniel Drake' <dsd@...top.org>, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	'Jingoo Han' <jg1.han@...sung.com>
Subject: Re: [PATCH] i2c: busses: i2c-pxa.c:  Fix for possible null pointer
 dereference

On Monday, June 02, 2014 5:27 AM, Wolfram Sang wrote:
> On Sat, May 17, 2014 at 07:14:08PM +0200, Rickard Strandqvist wrote:
> > There is otherwise a risk of a possible null pointer dereference.
> >
> > Was largely found by using a static code analysis program called cppcheck.
> 
> It is useful to put the output of the analyzer here.
> 
> >
> > Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
> > ---
> >  drivers/i2c/busses/i2c-pxa.c |    4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> > index bbe6dfb..dbe5ebe 100644
> > --- a/drivers/i2c/busses/i2c-pxa.c
> > +++ b/drivers/i2c/busses/i2c-pxa.c
> > @@ -1269,7 +1269,9 @@ eremap:
> >  eclk:
> >  	kfree(i2c);
> >  emalloc:
> > -	release_mem_region(res->start, resource_size(res));
> > +	if(res) {
> > +		release_mem_region(res->start, resource_size(res));
> > +	}
> 
> The proper fix is to move the release to the proper place, before kfree.
> Even better would probably be a devm_* conversion.

+1

I agree with Wolfram Sang's opinion. Please call release_mem_region()
prior to kfree().

One more thing, don't use braces when a single statement
is used. Please refer to 'Chapter 3: Placing Braces and Spaces'
of 'Documentation/CodingStyle'.

Best regards,
Jingoo Han

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