Re: [PATCH 4/5] mlxsw: spectrum_router: Annotate struct mlxsw_sp_nexthop_group_info with __counted_by

Justin Stitt
2023-10-03T23:13:00Z

On Fri, Sep 29, 2023 at 11:08 AM Kees Cook <keescook@chromium.org> wrote:
>
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct mlxsw_sp_nexthop_group_info.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Ido Schimmel <idosch@nvidia.com>
> Cc: Petr Machata <petrm@nvidia.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---

Reviewed-by: Justin Stitt <justinstitt@google.com>

> drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> index debd2c466f11..82a95125d9ca 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> @@ -3107,7 +3107,7 @@ struct mlxsw_sp_nexthop_group_info {
> gateway:1, /* routes using the group use a gateway */
> is_resilient:1;
> struct list_head list; /* member in nh_res_grp_list */
> - struct mlxsw_sp_nexthop nexthops[];
> + struct mlxsw_sp_nexthop nexthops[] __counted_by(count);
> };
>
> static struct mlxsw_sp_rif *
> --
> 2.34.1
>
>
Thanks
Justin