2023-03-06 23:51:33

by Gustavo A. R. Silva

[permalink] [raw]
Subject: [PATCH][next] net/mlx4_en: Replace fake flex-array with flexible-array member

Zero-length arrays as fake flexible arrays are deprecated and we are
moving towards adopting C99 flexible-array members instead.

Transform zero-length array into flexible-array member in struct
mlx4_en_rx_desc.

Address the following warnings found with GCC-13 and
-fstrict-flex-arrays=3 enabled:
drivers/net/ethernet/mellanox/mlx4/en_rx.c:88:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
drivers/net/ethernet/mellanox/mlx4/en_rx.c:149:30: warning: array subscript 0 is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
drivers/net/ethernet/mellanox/mlx4/en_rx.c:127:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
drivers/net/ethernet/mellanox/mlx4/en_rx.c:128:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
drivers/net/ethernet/mellanox/mlx4/en_rx.c:129:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
drivers/net/ethernet/mellanox/mlx4/en_rx.c:117:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
drivers/net/ethernet/mellanox/mlx4/en_rx.c:119:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [1].

Link: https://github.com/KSPP/linux/issues/21
Link: https://github.com/KSPP/linux/issues/264
Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index 544e09b97483..034733b13b1a 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -323,7 +323,7 @@ struct mlx4_en_tx_ring {

struct mlx4_en_rx_desc {
/* actual number of entries depends on rx ring stride */
- struct mlx4_wqe_data_seg data[0];
+ DECLARE_FLEX_ARRAY(struct mlx4_wqe_data_seg, data);
};

struct mlx4_en_rx_ring {
--
2.34.1



2023-03-07 06:08:02

by Tariq Toukan

[permalink] [raw]
Subject: Re: [PATCH][next] net/mlx4_en: Replace fake flex-array with flexible-array member



On 07/03/2023 1:51, Gustavo A. R. Silva wrote:
> Zero-length arrays as fake flexible arrays are deprecated and we are
> moving towards adopting C99 flexible-array members instead.
>
> Transform zero-length array into flexible-array member in struct
> mlx4_en_rx_desc.
>
> Address the following warnings found with GCC-13 and
> -fstrict-flex-arrays=3 enabled:
> drivers/net/ethernet/mellanox/mlx4/en_rx.c:88:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
> drivers/net/ethernet/mellanox/mlx4/en_rx.c:149:30: warning: array subscript 0 is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
> drivers/net/ethernet/mellanox/mlx4/en_rx.c:127:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
> drivers/net/ethernet/mellanox/mlx4/en_rx.c:128:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
> drivers/net/ethernet/mellanox/mlx4/en_rx.c:129:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
> drivers/net/ethernet/mellanox/mlx4/en_rx.c:117:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
> drivers/net/ethernet/mellanox/mlx4/en_rx.c:119:30: warning: array subscript i is outside array bounds of ‘struct mlx4_wqe_data_seg[0]’ [-Warray-bounds=]
>
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [1].
>
> Link: https://github.com/KSPP/linux/issues/21
> Link: https://github.com/KSPP/linux/issues/264
> Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> index 544e09b97483..034733b13b1a 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> @@ -323,7 +323,7 @@ struct mlx4_en_tx_ring {
>
> struct mlx4_en_rx_desc {
> /* actual number of entries depends on rx ring stride */
> - struct mlx4_wqe_data_seg data[0];
> + DECLARE_FLEX_ARRAY(struct mlx4_wqe_data_seg, data);
> };
>
> struct mlx4_en_rx_ring {

Reviewed-by: Tariq Toukan <[email protected]>

Thanks for your patch.