Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) client-ip=2620:137:e000::3:6;
Date:   Wed, 4 Oct 2023 21:55:48 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Justin Stitt <justinstitt@google.com>
Cc:     =?utf-8?Q?=C5=81ukasz?= Stelmach <l.stelmach@samsung.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] net: ax88796c: replace deprecated strncpy with strscpy
Message-ID: <202310042155.BDF8674@keescook>
References: <20231005-strncpy-drivers-net-ethernet-asix-ax88796c_ioctl-c-v1-1-6fafdc38b170@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20231005-strncpy-drivers-net-ethernet-asix-ax88796c_ioctl-c-v1-1-6fafdc38b170@google.com>
Precedence: bulk

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