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[82.0.78.162]) by smtp.gmail.com with ESMTPSA id v7-20020adfedc7000000b003197efd1e7bsm19072675wro.114.2023.10.12.13.55.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Oct 2023 13:55:41 -0700 (PDT) Subject: Re: [PATCH] sfc: replace deprecated strncpy with strscpy To: Justin Stitt , Martin Habets , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-net-drivers@amd.com, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org References: <20231012-strncpy-drivers-net-ethernet-sfc-mcdi-c-v1-1-478c8de1039d@google.com> From: Edward Cree Message-ID: Date: Thu, 12 Oct 2023 21:55:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20231012-strncpy-drivers-net-ethernet-sfc-mcdi-c-v1-1-478c8de1039d@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-5.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,NICE_REPLY_A, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On 12/10/2023 21:38, 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. > > `desc` is expected to be NUL-terminated as evident by the manual > NUL-byte assignment. Moreover, NUL-padding does not seem to be > necessary. > > The only caller of efx_mcdi_nvram_metadata() is > efx_devlink_info_nvram_partition() which provides a NULL for `desc`: > | rc = efx_mcdi_nvram_metadata(efx, partition_type, NULL, version, NULL, 0); > > Due to this, I am not sure this code is even reached but we should still > favor something other than strncpy. > > 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 Acked-by: Edward Cree but ideally we should just rip out the dead code instead. If this patch gets taken as-is into net-next then I can probably do that in a follow-up. -ed