Re: [PATCH] kernel: module: Use struct_size() helper

[Jessica Yu]

+++ Gustavo A. R. Silva [04/06/19 18:23 -0500]:
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes, in particular in the
> context in which this code is being used.
>
> So, replace the following form:
>
> sizeof(*sect_attrs) + nloaded * sizeof(sect_attrs->attrs[0]
>
> with:
>
> struct_size(sect_attrs, attrs, nloaded)
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>

Hi Gustavo!

I see you've sent similar cleanup patches elsewhere, do you think you
could reword your commit message to be more similar to your patch here
for instance:

	https://lkml.org/lkml/2019/6/5/856

It does a *much* better job of explaining the motivation and usage of
struct_size().

Thank you!

Jessica

> ---
> kernel/module.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 80c7c09584cf..3f3bb090fbf4 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -1492,8 +1492,7 @@ static void add_sect_attrs(struct module *mod, const struct load_info *info)
> 	for (i = 0; i < info->hdr->e_shnum; i++)
> 		if (!sect_empty(&info->sechdrs[i]))
> 			nloaded++;
> -	size[0] = ALIGN(sizeof(*sect_attrs)
> -			+ nloaded * sizeof(sect_attrs->attrs[0]),
> +	size[0] = ALIGN(struct_size(sect_attrs, attrs, nloaded),
> 			sizeof(sect_attrs->grp.attrs[0]));
> 	size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.attrs[0]);
> 	sect_attrs = kzalloc(size[0] + size[1], GFP_KERNEL);
> --
> 2.21.0