On Thu, Feb 21, 2019 at 09:37:38AM -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;
> struct boo entry[];
> };
>
> size = sizeof(struct foo) + count * sizeof(struct boo);
> instance = kzalloc(size, 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);
>
> Notice that, in this case, variable size is not necessary, hence
> it is removed.
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
Applied, thank you.
> ---
> drivers/input/evdev.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index f48369d6f3a0..ee8dd8b1b09e 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -503,14 +503,13 @@ static int evdev_open(struct inode *inode, struct file
> *file)
> {
> struct evdev *evdev = container_of(inode->i_cdev, struct evdev, cdev);
> unsigned int bufsize = evdev_compute_buffer_size(evdev->handle.dev);
> - unsigned int size = sizeof(struct evdev_client) +
> - bufsize * sizeof(struct input_event);
> struct evdev_client *client;
> int error;
>
> - client = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
> + client = kzalloc(struct_size(client, buffer, bufsize),
> + GFP_KERNEL | __GFP_NOWARN);
> if (!client)
> - client = vzalloc(size);
> + client = vzalloc(struct_size(client, buffer, bufsize));
> if (!client)
> return -ENOMEM;
>
> --
> 2.20.1
>
--
Dmitry
