Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.38 as permitted sender) client-ip=23.128.96.38;
Date:   Wed, 11 Oct 2023 14:30:54 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Justin Stitt <justinstitt@google.com>
Cc:     Tariq Toukan <tariqt@nvidia.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-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org
Subject: Re: [PATCH] net/mlx4_core: replace deprecated strncpy with strscpy
Message-ID: <202310111430.C419092@keescook>
References: <20231011-strncpy-drivers-net-ethernet-mellanox-mlx4-fw-c-v1-1-4d7b5d34c933@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20231011-strncpy-drivers-net-ethernet-mellanox-mlx4-fw-c-v1-1-4d7b5d34c933@google.com>
Precedence: bulk

On Wed, Oct 11, 2023 at 09:04:37PM +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 expect `dst` to be NUL-terminated based on its use with format
> strings:
> |       mlx4_dbg(dev, "Reporting Driver Version to FW: %s\n", dst);
> 
> Moreover, NUL-padding is not required.

Yup, since it's only use is for the above report.

> 
> Considering the above, 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>

Thanks!

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

-- 
Kees Cook