[PATCH] net: liquidio: replace deprecated strncpy with strscpy_pad

[PATCH] net: liquidio: replace deprecated strncpy with strscpy_pad

[Justin Stitt]

`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: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
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 <justinstitt@google.com>

Re: [PATCH] net: liquidio: replace deprecated strncpy with strscpy_pad

[Kees Cook]

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: linux-hardening@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Looks like a safe replacement with strscpy_pad().

Reviewed-by: Kees Cook <keescook@chromium.org>

> ---
> 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 <justinstitt@google.com>
> 
> 

-- 
Kees Cook

Re: [PATCH] net: liquidio: replace deprecated strncpy with strscpy_pad

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 05 Oct 2023 21:41:01 +0000 you 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);
> 
> [...]

Here is the summary with links:
  - net: liquidio: replace deprecated strncpy with strscpy_pad
    https://git.kernel.org/netdev/net-next/c/092b0be65032

You are awesome, thank you!
-- 
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