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

Gustavo A. R. Silva
2020-06-16T22:23:22Z

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@redhat.com 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@embeddedor.com>
> ---
> 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;
>