[PATCH] mtd: rawnand: atmel: use struct_size() in devm_kzalloc()

[PATCH] mtd: rawnand: atmel: use struct_size() in devm_kzalloc()

[Gustavo A. R. Silva]

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 <gustavo@embeddedor.com>
---
 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

Re: [PATCH] mtd: rawnand: atmel: use struct_size() in devm_kzalloc()

[Kees Cook]

On Thu, Aug 23, 2018 at 6:09 PM, Gustavo A. R. Silva
<gustavo@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 <gustavo@embeddedor.com>

Reviewed-by: Kees Cook <keescook@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

Re: [PATCH] mtd: rawnand: atmel: use struct_size() in devm_kzalloc()

[Boris Brezillon]

Hi Gustavo,

On Thu, 23 Aug 2018 20:09:38 -0500
"Gustavo A. R. Silva" <gustavo@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 <gustavo@embeddedor.com>

Can we have all NAND controller drivers patched in a single patch
instead of having one patch per-driver?

Thanks,

Boris

Re: [PATCH] mtd: rawnand: atmel: use struct_size() in devm_kzalloc()

[Miquel Raynal]

Hi Gustavo,

"Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote on Thu, 23 Aug
2018 20:09:38 -0500:

> 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 <gustavo@embeddedor.com>
> ---

Applied to nand/next.

Thanks,
Miquèl