Re: [PATCH] RDMA/ucma: Use struct_size() helper

[Leon Romanovsky]

On Tue, Jun 04, 2019 at 10:42:22AM -0500, Gustavo A. R. Silva wrote:
> 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.

What does "in particular in the context in which this code is being
used" mean?

>
> So, replace the following form:
>
> sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))
>
> with:
>
> struct_size(resp, path_data, i)

It is already written inside commit itself.

>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> ---
>  drivers/infiniband/core/ucma.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
> index 140a338a135f..cbe460076611 100644
> --- a/drivers/infiniband/core/ucma.c
> +++ b/drivers/infiniband/core/ucma.c
> @@ -951,8 +951,7 @@ static ssize_t ucma_query_path(struct ucma_context *ctx,
>  		}
>  	}
>
> -	if (copy_to_user(response, resp,
> -			 sizeof(*resp) + (i * sizeof(struct ib_path_rec_data))))
> +	if (copy_to_user(response, resp, struct_size(resp, path_data, i)))
>  		ret = -EFAULT;
>
>  	kfree(resp);
> --
> 2.21.0
>