[PATCH] memory: atmel-ebi: Use struct_size() in devm_kzalloc()

[PATCH] memory: atmel-ebi: 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/memory/atmel-ebi.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/memory/atmel-ebi.c b/drivers/memory/atmel-ebi.c
index b907865..c3748b4 100644
--- a/drivers/memory/atmel-ebi.c
+++ b/drivers/memory/atmel-ebi.c
@@ -327,8 +327,7 @@ static int atmel_ebi_dev_setup(struct atmel_ebi *ebi, struct device_node *np,
 		return -EINVAL;
 	}
 
-	ebid = devm_kzalloc(ebi->dev,
-			    sizeof(*ebid) + (numcs * sizeof(*ebid->configs)),
+	ebid = devm_kzalloc(ebi->dev, struct_size(ebid, configs, numcs),
 			    GFP_KERNEL);
 	if (!ebid)
 		return -ENOMEM;
-- 
2.7.4

Re: [PATCH] memory: atmel-ebi: Use struct_size() in devm_kzalloc()

[Kees Cook]

On Thu, Aug 23, 2018 at 6:07 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/memory/atmel-ebi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/memory/atmel-ebi.c b/drivers/memory/atmel-ebi.c
> index b907865..c3748b4 100644
> --- a/drivers/memory/atmel-ebi.c
> +++ b/drivers/memory/atmel-ebi.c
> @@ -327,8 +327,7 @@ static int atmel_ebi_dev_setup(struct atmel_ebi *ebi, struct device_node *np,
>                 return -EINVAL;
>         }
>
> -       ebid = devm_kzalloc(ebi->dev,
> -                           sizeof(*ebid) + (numcs * sizeof(*ebid->configs)),
> +       ebid = devm_kzalloc(ebi->dev, struct_size(ebid, configs, numcs),
>                             GFP_KERNEL);
>         if (!ebid)
>                 return -ENOMEM;
> --
> 2.7.4
>



-- 
Kees Cook
Pixel Security

Re: [PATCH] memory: atmel-ebi: Use struct_size() in devm_kzalloc()

[Alexandre Belloni]

On 23/08/2018 20:07:06-0500, Gustavo A. R. Silva 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>
> ---
>  drivers/memory/atmel-ebi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
Applied, thanks.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com