2014-06-01 20:27:00

by Wolfram Sang

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

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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 <[email protected]>
> ---
> 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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2014-06-02 01:55:48

by Jingoo Han

[permalink] [raw]

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 <[email protected]>
> > ---
> > 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