On Thu, Oct 05, 2023 at 09:41:01PM +0000, 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 know `fw_type` must be NUL-terminated based on use here:
> | static bool fw_type_is_auto(void)
> | {
> | return strncmp(fw_type, LIO_FW_NAME_TYPE_AUTO,
> | sizeof(LIO_FW_NAME_TYPE_AUTO)) == 0;
> | }
> ...and here
> | module_param_string(fw_type, fw_type, sizeof(fw_type), 0444);
>
> Let's opt to NUL-pad the destination buffer as well so that we maintain
> the same exact behavior that `strncpy` provided here.
>
> A suitable replacement is `strscpy_pad` due to the fact that it
> guarantees both NUL-termination and NUL-padding on the destination
> buffer.
>
> Link:
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> [1]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
Looks like a safe replacement with strscpy_pad().
Reviewed-by: Kees Cook <[email protected]>
> ---
> Note: build-tested only.
> ---
> drivers/net/ethernet/cavium/liquidio/lio_main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c
> b/drivers/net/ethernet/cavium/liquidio/lio_main.c
> index 100daadbea2a..34f02a8ec2ca 100644
> --- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
> +++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
> @@ -1689,7 +1689,7 @@ static int load_firmware(struct octeon_device *oct)
>
> if (fw_type_is_auto()) {
> tmp_fw_type = LIO_FW_NAME_TYPE_NIC;
> - strncpy(fw_type, tmp_fw_type, sizeof(fw_type));
> + strscpy_pad(fw_type, tmp_fw_type, sizeof(fw_type));
> } else {
> tmp_fw_type = fw_type;
> }
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id:
> 20231005-strncpy-drivers-net-ethernet-cavium-liquidio-lio_main-c-b05f78661635
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>
>
--
Kees Cook
