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[34.123.74.161]) by smtp.gmail.com with ESMTPSA id ee24-20020a056638293800b004332f6537e2sm3057256jab.83.2023.10.10.15.42.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Oct 2023 15:42:48 -0700 (PDT) Date: Tue, 10 Oct 2023 22:42:45 +0000 From: Justin Stitt To: Jesse Brandeburg , Tony Nguyen , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] igc: replace deprecated strncpy with strscpy Message-ID: <20231010224245.i57oix72csm7kjp7@google.com> References: <20231010-strncpy-drivers-net-ethernet-intel-igc-igc_main-c-v1-1-f1f507ecc476@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231010-strncpy-drivers-net-ethernet-intel-igc-igc_main-c-v1-1-f1f507ecc476@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 10, 2023 at 09:15:39PM +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 netdev->name to be NUL-terminated based on its use with format > strings: > | if (q_vector->rx.ring && q_vector->tx.ring) > | sprintf(q_vector->name, "%s-TxRx-%u", netdev->name, > > Furthermore, we do not need NUL-padding as netdev is already > zero-allocated: > | netdev = alloc_etherdev_mq(sizeof(struct igc_adapter), > | IGC_MAX_TX_QUEUES); > ... > alloc_etherdev() -> alloc_etherdev_mq() -> alloc_etherdev_mqs() -> > alloc_netdev_mqs() ... > | p = kvzalloc(alloc_size, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL); > > 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. > > Let's also opt for the more idiomatic strscpy usage of (dest, src, > sizeof(dest)) instead of (dest, src, SOME_LEN). > > 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 > --- > Note: build-tested only. > --- > drivers/net/ethernet/intel/igc/igc_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c > index 98de34d0ce07..e9bb403bbacf 100644 > --- a/drivers/net/ethernet/intel/igc/igc_main.c > +++ b/drivers/net/ethernet/intel/igc/igc_main.c > @@ -6935,7 +6935,7 @@ static int igc_probe(struct pci_dev *pdev, > */ > igc_get_hw_control(adapter); > > - strncpy(netdev->name, "eth%d", IFNAMSIZ); > + strscpy(netdev->name, "eth%d", sizeof(netdev->name)); > err = register_netdev(netdev); > if (err) > goto err_register; > > --- > base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 > change-id: 20231010-strncpy-drivers-net-ethernet-intel-igc-igc_main-c-26efa209ddb5 > > Best regards, > -- > Justin Stitt > Hi, this patch was bundled up with some others. It has a new home: https://lore.kernel.org/all/20231010-netdev-replace-strncpy-resend-as-series-v1-0-caf9f0f2f021@google.com/