Re: [PATCH] staging:iio: Use kcalloc instead of kzalloc to allocatearray

[J.I. Cameron]

On Nov 30 2011, Dan Carpenter wrote:

> On Tue, Nov 29, 2011 at 10:08:00PM +0100, Thomas Meyer wrote:
> > The advantage of kcalloc is, that will prevent integer overflows which could
> > result from the multiplication of number of elements and size and it is also
> > a bit nicer to read.
> >
> > The semantic patch that makes this change is available
> > in https://lkml.org/lkml/2011/11/25/107
Fine by me. Thanks.  As stated by others though you might want to change the description
to not imply it's mainly about overflows.
> > Signed-off-by: Thomas Meyer <thomas@xxxxxxxx>
Acked-by: Jonathan Cameron <jic23@xxxxxxxxxx>
> > ---
> >
> > diff -u -p a/drivers/staging/iio/accel/lis3l02dq_ring.c b/drivers/staging/iio/accel/lis3l02dq_ring.c
> > --- a/drivers/staging/iio/accel/lis3l02dq_ring.c 2011-11-13 11:07:47.933826988 +0100
> > +++ b/drivers/staging/iio/accel/lis3l02dq_ring.c 2011-11-28 20:00:44.704446880 +0100
> > @@ -93,8 +93,7 @@ static int lis3l02dq_read_all(struct iio
> >  	struct spi_message msg;
> >  	int ret, i, j = 0;
> >  
> > -	xfers = kzalloc((buffer->scan_count) * 2
> > -			* sizeof(*xfers), GFP_KERNEL);
> > +	xfers = kcalloc((buffer->scan_count) * 2, sizeof(*xfers), GFP_KERNEL);
>
> I've looked at these and none of them can actually overflow.
>
> But if they could then there would still be the potential for
> overflow here.  If buffer->scan_count were a negative number then
> the first for loop could cause memory corruption.
>
> Still it's a cleanup and the patch is fine.
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