net: ax88796c: replace deprecated strncpy with strscpy

[PATCH] net: ax88796c: replace deprecated strncpy with strscpy

Posted by Justin Stitt 2 years, 3 months ago

`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer without
unnecessarily NUL-padding.

It should be noted that there doesn't currently exist a bug here as
DRV_NAME is a small string literal which means no overread bugs are
present.

Also to note, other ethernet drivers are using strscpy in a similar
pattern:
|       dec/tulip/tulip_core.c
|       861:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
|
|       8390/ax88796.c
|       582:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
|
|       dec/tulip/dmfe.c
|       1077:   strscpy(info->driver, DRV_NAME, sizeof(info->driver));
|
|       8390/etherh.c
|       558:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));

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@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested only.
---
 drivers/net/ethernet/asix/ax88796c_ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/asix/ax88796c_ioctl.c b/drivers/net/ethernet/asix/ax88796c_ioctl.c
index 916ae380a004..7d2fe2e5af92 100644
--- a/drivers/net/ethernet/asix/ax88796c_ioctl.c
+++ b/drivers/net/ethernet/asix/ax88796c_ioctl.c
@@ -24,7 +24,7 @@ static void
 ax88796c_get_drvinfo(struct net_device *ndev, struct ethtool_drvinfo *info)
 {
 	/* Inherit standard device info */
-	strncpy(info->driver, DRV_NAME, sizeof(info->driver));
+	strscpy(info->driver, DRV_NAME, sizeof(info->driver));
 }
 
 static u32 ax88796c_get_msglevel(struct net_device *ndev)

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231005-strncpy-drivers-net-ethernet-asix-ax88796c_ioctl-c-56af20b7d992

Best regards,
--
Justin Stitt <justinstitt@google.com>

Re: [PATCH] net: ax88796c: replace deprecated strncpy with strscpy

Posted by patchwork-bot+netdevbpf@kernel.org 2 years, 2 months ago

Hello:

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

On Thu, 05 Oct 2023 01:06:26 +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.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
> 
> [...]

Here is the summary with links:
  - net: ax88796c: replace deprecated strncpy with strscpy
    https://git.kernel.org/netdev/net-next/c/9c9e3ab20f35

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH] net: ax88796c: replace deprecated strncpy with strscpy

Posted by Lukasz Stelmach 2 years, 2 months ago

It was <2023-10-05 czw 01:06>, when 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.
>
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
>
> It should be noted that there doesn't currently exist a bug here as
> DRV_NAME is a small string literal which means no overread bugs are
> present.
>
> Also to note, other ethernet drivers are using strscpy in a similar
> pattern:
> |       dec/tulip/tulip_core.c
> |       861:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       8390/ax88796.c
> |       582:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       dec/tulip/dmfe.c
> |       1077:   strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       8390/etherh.c
> |       558:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
>
> 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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> ---
> Note: build-tested only.
> ---
>  drivers/net/ethernet/asix/ax88796c_ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Reviewed-by: Lukasz Stelmach <l.stelmach@samsung.com>

> diff --git a/drivers/net/ethernet/asix/ax88796c_ioctl.c b/drivers/net/ethernet/asix/ax88796c_ioctl.c
> index 916ae380a004..7d2fe2e5af92 100644
> --- a/drivers/net/ethernet/asix/ax88796c_ioctl.c
> +++ b/drivers/net/ethernet/asix/ax88796c_ioctl.c
> @@ -24,7 +24,7 @@ static void
>  ax88796c_get_drvinfo(struct net_device *ndev, struct ethtool_drvinfo *info)
>  {
>  	/* Inherit standard device info */
> -	strncpy(info->driver, DRV_NAME, sizeof(info->driver));
> +	strscpy(info->driver, DRV_NAME, sizeof(info->driver));
>  }
>  
>  static u32 ax88796c_get_msglevel(struct net_device *ndev)
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id: 20231005-strncpy-drivers-net-ethernet-asix-ax88796c_ioctl-c-56af20b7d992
>
> Best regards,
> --
> Justin Stitt <justinstitt@google.com>
>
>
>

-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

Re: [PATCH] net: ax88796c: replace deprecated strncpy with strscpy

Posted by Kees Cook 2 years, 2 months ago

On Thu, Oct 05, 2023 at 01:06:26AM +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.
> 
> A suitable replacement is `strscpy` [2] due to the fact that it
> guarantees NUL-termination on the destination buffer without
> unnecessarily NUL-padding.
> 
> It should be noted that there doesn't currently exist a bug here as
> DRV_NAME is a small string literal which means no overread bugs are
> present.
> 
> Also to note, other ethernet drivers are using strscpy in a similar
> pattern:
> |       dec/tulip/tulip_core.c
> |       861:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       8390/ax88796.c
> |       582:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       dec/tulip/dmfe.c
> |       1077:   strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> |
> |       8390/etherh.c
> |       558:    strscpy(info->driver, DRV_NAME, sizeof(info->driver));
> 
> 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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Yeah, this looks like the others.

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

-- 
Kees Cook