Re: [PATCH] dm ioctl: Use struct_size() helper

[Gustavo A. R. Silva]

Hi all,

Friendly ping: who can take this?

It's been almost a year... and I just noticed there was a problem
with the email addresses back then...

I just fixed the issue and this patch should now appear on
dm-devel@xxxxxxxxxx and LKML.

Thanks
--
Gustavo

On 8/28/19 13:38, 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 dm_target_deps {
> 	...
>         __u64 dev[0];   /* out */
> };
> 
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes.
> 
> So, replace the following form:
> 
> sizeof(*deps) + (sizeof(*deps->dev) * count)
> 
> with:
> 
> struct_size(deps, dev, count)
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> ---
>  drivers/md/dm-ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
> index fb6f8fb1f13d..b2d52cec70d4 100644
> --- a/drivers/md/dm-ioctl.c
> +++ b/drivers/md/dm-ioctl.c
> @@ -1446,7 +1446,7 @@ static void retrieve_deps(struct dm_table *table,
>  	/*
>  	 * Check we have enough space.
>  	 */
> -	needed = sizeof(*deps) + (sizeof(*deps->dev) * count);
> +	needed = struct_size(deps, dev, count);
>  	if (len < needed) {
>  		param->flags |= DM_BUFFER_FULL_FLAG;
>  		return;
>