Re: [PATCH v2] RDMA/mlx5: Use memset_after() to zero struct mlx5_ib_mr

Gustavo A. R. Silva
2021-12-14T00:33:36Z

On Tue, Dec 07, 2021 at 01:20:22PM -0800, Kees Cook wrote:
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memset(), avoid intentionally writing across
> neighboring fields.
>
> Use memset_after() to zero the end of struct mlx5_ib_mr that should
> be initialized.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

> ---
> v2: rebased, umem moved into the union and is expected to be wiped
> https://lore.kernel.org/lkml/20211207194525.GL6385@nvidia.com
> ---
> drivers/infiniband/hw/mlx5/mlx5_ib.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
> index 4a7a56ed740b..ded10719b643 100644
> --- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
> +++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
> @@ -664,8 +664,8 @@ struct mlx5_ib_mr {
>
> /* User MR data */
> struct mlx5_cache_ent *cache_ent;
> + /* Everything after cache_ent is zero'd when MR allocated */
>
> - /* This is zero'd when the MR is allocated */
> union {
> /* Used only while the MR is in the cache */
> struct {
> @@ -718,7 +718,7 @@ struct mlx5_ib_mr {
> /* Zero the fields in the mr that are variant depending on usage */
> static inline void mlx5_clear_mr(struct mlx5_ib_mr *mr)
> {
> - memset(mr->out, 0, sizeof(*mr) - offsetof(struct mlx5_ib_mr, out));
> + memset_after(mr, 0, cache_ent);
> }
>
> static inline bool is_odp_mr(struct mlx5_ib_mr *mr)
> --
> 2.30.2
>
>
>
>