Input: tca6416-keypad: use struct_size() in kzalloc()
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Message ID 20190108152816.GA7486@embeddedor
State Accepted
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Series
  • Input: tca6416-keypad: use struct_size() in kzalloc()
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Commit Message

Gustavo A. R. Silva Jan. 8, 2019, 3:28 p.m. UTC
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 = kzalloc(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 = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/input/keyboard/tca6416-keypad.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Comments

Dmitry Torokhov Jan. 12, 2019, 1:47 a.m. UTC | #1
On Tue, Jan 08, 2019 at 09:28:16AM -0600, 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 = kzalloc(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 = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Applied, thank you.

> ---
>  drivers/input/keyboard/tca6416-keypad.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/input/keyboard/tca6416-keypad.c b/drivers/input/keyboard/tca6416-keypad.c
> index dc983ab6c0ad..cdeef180aead 100644
> --- a/drivers/input/keyboard/tca6416-keypad.c
> +++ b/drivers/input/keyboard/tca6416-keypad.c
> @@ -219,9 +219,7 @@ static int tca6416_keypad_probe(struct i2c_client *client,
>  		return -EINVAL;
>  	}
>  
> -	chip = kzalloc(sizeof(struct tca6416_keypad_chip) +
> -		       pdata->nbuttons * sizeof(struct tca6416_button),
> -		       GFP_KERNEL);
> +	chip = kzalloc(struct_size(chip, buttons, pdata->nbuttons), GFP_KERNEL);
>  	input = input_allocate_device();
>  	if (!chip || !input) {
>  		error = -ENOMEM;
> -- 
> 2.20.1
>

Patch
diff mbox series

diff --git a/drivers/input/keyboard/tca6416-keypad.c b/drivers/input/keyboard/tca6416-keypad.c
index dc983ab6c0ad..cdeef180aead 100644
--- a/drivers/input/keyboard/tca6416-keypad.c
+++ b/drivers/input/keyboard/tca6416-keypad.c
@@ -219,9 +219,7 @@  static int tca6416_keypad_probe(struct i2c_client *client,
 		return -EINVAL;
 	}
 
-	chip = kzalloc(sizeof(struct tca6416_keypad_chip) +
-		       pdata->nbuttons * sizeof(struct tca6416_button),
-		       GFP_KERNEL);
+	chip = kzalloc(struct_size(chip, buttons, pdata->nbuttons), GFP_KERNEL);
 	input = input_allocate_device();
 	if (!chip || !input) {
 		error = -ENOMEM;