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

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Date:	Sun, 1 Jun 2014 22:26:47 +0200
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
Cc:	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Jingoo Han <jg1.han@...sung.com>,
	Leilei Shang <shangll@...vell.com>,
	Daniel Drake <dsd@...top.org>, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH] i2c: busses: i2c-pxa.c:  Fix for possible null pointer
 dereference

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.


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