[PATCH] liquidio: replace deprecated strncpy with strscpy

[PATCH] liquidio: replace deprecated strncpy with strscpy

[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.

NUL-padding is not required as rep_cfg is memset to 0:
|       memset(&rep_cfg, 0, sizeof(rep_cfg));

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@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: build-tested only.
---
 drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c b/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
index 600de587d7a9..aa6c0dfb6f1c 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
@@ -638,7 +638,8 @@ lio_vf_rep_netdev_event(struct notifier_block *nb,
 	memset(&rep_cfg, 0, sizeof(rep_cfg));
 	rep_cfg.req_type = LIO_VF_REP_REQ_DEVNAME;
 	rep_cfg.ifidx = vf_rep->ifidx;
-	strncpy(rep_cfg.rep_name.name, ndev->name, LIO_IF_NAME_SIZE);
+	strscpy(rep_cfg.rep_name.name, ndev->name,
+		sizeof(rep_cfg.rep_name.name));
 
 	ret = lio_vf_rep_send_soft_command(oct, &rep_cfg,
 					   sizeof(rep_cfg), NULL, 0);

---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231005-strncpy-drivers-net-ethernet-cavium-liquidio-lio_vf_rep-c-b23567b42939

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

Re: [PATCH] liquidio: replace deprecated strncpy with strscpy

[Kees Cook]

On Thu, Oct 05, 2023 at 09:55:06PM +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.
> 
> NUL-padding is not required as rep_cfg is memset to 0:
> |       memset(&rep_cfg, 0, sizeof(rep_cfg));
> 
> 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@vger.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@google.com>
> ---
> Note: build-tested only.
> ---
>  drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c b/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
> index 600de587d7a9..aa6c0dfb6f1c 100644
> --- a/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
> +++ b/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
> @@ -638,7 +638,8 @@ lio_vf_rep_netdev_event(struct notifier_block *nb,
>  	memset(&rep_cfg, 0, sizeof(rep_cfg));
>  	rep_cfg.req_type = LIO_VF_REP_REQ_DEVNAME;
>  	rep_cfg.ifidx = vf_rep->ifidx;
> -	strncpy(rep_cfg.rep_name.name, ndev->name, LIO_IF_NAME_SIZE);
> +	strscpy(rep_cfg.rep_name.name, ndev->name,
> +		sizeof(rep_cfg.rep_name.name));

struct lio_vf_rep_req {
	...
        union {
                struct lio_vf_rep_name {
                        char name[LIO_IF_NAME_SIZE];
                } rep_name;

Yup, sizeof(rep_cfg.rep_name.name) == LIO_IF_NAME_SIZE.

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

-- 
Kees Cook

Re: [PATCH] liquidio: replace deprecated strncpy with strscpy

[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 21:55:06 +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.
> 
> NUL-padding is not required as rep_cfg is memset to 0:
> |       memset(&rep_cfg, 0, sizeof(rep_cfg));
> 
> [...]

Here is the summary with links:
  - liquidio: replace deprecated strncpy with strscpy
    https://git.kernel.org/netdev/net-next/c/a16724289af0

You are awesome, thank you!
-- 
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