Re: [PATCH] net/mlx4_core: replace deprecated strncpy with strscpy

[Saeed Mahameed]

On 11 Oct 21:04, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> We expect `dst` to be NUL-terminated based on its use with format
> strings:
> |       mlx4_dbg(dev, "Reporting Driver Version to FW: %s\n", dst);
>
> Moreover, NUL-padding is not required.
>
> Considering the above, a suitable replacement is `strscpy` [2] due to
> the fact that it guarantees NUL-termination on the destination buffer
> without unnecessarily NUL-padding.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@xxxxxxxxxxxxxxx
> Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
> ---
> Note: build-tested only.
>
> Found with: $ rg "strncpy\("
> ---
> drivers/net/ethernet/mellanox/mlx4/fw.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/fw.c b/drivers/net/ethernet/mellanox/mlx4/fw.c
> index fe48d20d6118..0005d9e2c2d6 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/fw.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/fw.c
> @@ -1967,7 +1967,7 @@ int mlx4_INIT_HCA(struct mlx4_dev *dev, struct mlx4_init_hca_param *param)
> 	if (dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_DRIVER_VERSION_TO_FW) {
> 		u8 *dst = (u8 *)(inbox + INIT_HCA_DRIVER_VERSION_OFFSET / 4);
>
> -		strncpy(dst, DRV_NAME_FOR_FW, INIT_HCA_DRIVER_VERSION_SZ - 1);
> +		strscpy(dst, DRV_NAME_FOR_FW, INIT_HCA_DRIVER_VERSION_SZ);
> 		mlx4_dbg(dev, "Reporting Driver Version to FW: %s\n", dst);
> 	}
>
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id: 20231011-strncpy-drivers-net-ethernet-mellanox-mlx4-fw-c-67809559dd1a
>
> Best regards,
> --
> Justin Stitt <justinstitt@xxxxxxxxxx>

Reviewed-by: Saeed Mahameed <saeedm@xxxxxxxxxx>