Re: [PATCH 06/64] bnxt_en: Use struct_group_attr() for memcpy() region

Gustavo A. R. Silva
2021-07-28T04:42:50Z

On Tue, Jul 27, 2021 at 01:57:57PM -0700, Kees Cook wrote:
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memcpy(), memmove(), and memset(), avoid
> intentionally writing across neighboring fields.
>
> Use struct_group() around members queue_id, min_bw, max_bw, tsa, pri_lvl,
> and bw_weight so they can be referenced together. This will allow memcpy()
> and sizeof() to more easily reason about sizes, improve readability,
> and avoid future warnings about writing beyond the end of queue_id.
>
> "pahole" shows no size nor member offset changes to struct bnxt_cos2bw_cfg.
> "objdump -d" shows no meaningful object code changes (i.e. only source
> line number induced differences and optimizations).
>
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
--
Gustavo

> ---
> drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.c | 4 ++--
> drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.h | 14 ++++++++------
> 2 files changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.c
> index 8a68df4d9e59..95c636f89329 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.c
> @@ -148,10 +148,10 @@ static int bnxt_hwrm_queue_cos2bw_qcfg(struct bnxt *bp, struct ieee_ets *ets)
> }
>
> data = &resp->queue_id0 + offsetof(struct bnxt_cos2bw_cfg, queue_id);
> - for (i = 0; i < bp->max_tc; i++, data += sizeof(cos2bw) - 4) {
> + for (i = 0; i < bp->max_tc; i++, data += sizeof(cos2bw.cfg)) {
> int tc;
>
> - memcpy(&cos2bw.queue_id, data, sizeof(cos2bw) - 4);
> + memcpy(&cos2bw.cfg, data, sizeof(cos2bw.cfg));
> if (i == 0)
> cos2bw.queue_id = resp->queue_id0;
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.h b/drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.h
> index 6eed231de565..716742522161 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.h
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.h
> @@ -23,13 +23,15 @@ struct bnxt_dcb {
>
> struct bnxt_cos2bw_cfg {
> u8 pad[3];
> - u8 queue_id;
> - __le32 min_bw;
> - __le32 max_bw;
> + struct_group_attr(cfg, __packed,
> + u8 queue_id;
> + __le32 min_bw;
> + __le32 max_bw;
> #define BW_VALUE_UNIT_PERCENT1_100 (0x1UL << 29)
> - u8 tsa;
> - u8 pri_lvl;
> - u8 bw_weight;
> + u8 tsa;
> + u8 pri_lvl;
> + u8 bw_weight;
> + );
> u8 unused;
> };
>
> --
> 2.30.2
>