On Thu, Aug 23, 2018 at 6:09 PM, Gustavo A. R. Silva
<gust...@embeddedor.com> wrote:
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
>
> struct foo {
> int stuff;
> void *entry[];
> };
>
> instance = devm_kzalloc(dev, sizeof(struct foo) + sizeof(void *) * count,
> GFP_KERNEL);
>
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
>
> instance = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);
>
> This issue was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com>
Reviewed-by: Kees Cook <keesc...@chromium.org>
-Kees
> ---
> drivers/mtd/nand/raw/atmel/nand-controller.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c
> b/drivers/mtd/nand/raw/atmel/nand-controller.c
> index a068b21..b17cfd0 100644
> --- a/drivers/mtd/nand/raw/atmel/nand-controller.c
> +++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
> @@ -1586,9 +1586,7 @@ static struct atmel_nand *atmel_nand_create(struct
> atmel_nand_controller *nc,
> return ERR_PTR(-EINVAL);
> }
>
> - nand = devm_kzalloc(nc->dev,
> - sizeof(*nand) + (numcs * sizeof(*nand->cs)),
> - GFP_KERNEL);
> + nand = devm_kzalloc(nc->dev, struct_size(nand, cs, numcs),
> GFP_KERNEL);
> if (!nand) {
> dev_err(nc->dev, "Failed to allocate NAND object\n");
> return ERR_PTR(-ENOMEM);
> --
> 2.7.4
>
--
Kees Cook
Pixel Security
