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[34.123.74.161]) by smtp.gmail.com with ESMTPSA id q21-20020a02a315000000b0042b2df337ccsm2907113jai.76.2023.10.10.15.35.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Oct 2023 15:35:28 -0700 (PDT) Date: Tue, 10 Oct 2023 22:35:26 +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] e100: replace deprecated strncpy with strscpy Message-ID: <20231010223526.2qc4q64txfoi64lq@google.com> References: <20231009-strncpy-drivers-net-ethernet-intel-e100-c-v1-1-ca0ff96868a3@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231009-strncpy-drivers-net-ethernet-intel-e100-c-v1-1-ca0ff96868a3@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 09, 2023 at 11:41:01PM +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. > > The "...-1" pattern makes it evident that netdev->name is expected to be > NUL-terminated. > > Meanwhile, it seems NUL-padding is not required due to alloc_etherdev > zero-allocating the buffer. > > 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. > > This is in line with other uses of strscpy on netdev->name: > $ rg "strscpy\(netdev\->name.*pci.*" > > drivers/net/ethernet/intel/e1000e/netdev.c > 7455: strscpy(netdev->name, pci_name(pdev), sizeof(netdev->name)); > > drivers/net/ethernet/intel/ixgbe/ixgbe_main.c > 10839: strscpy(netdev->name, pci_name(pdev), sizeof(netdev->name)); > > 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/e100.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/intel/e100.c b/drivers/net/ethernet/intel/e100.c > index d3fdc290937f..01f0f12035ca 100644 > --- a/drivers/net/ethernet/intel/e100.c > +++ b/drivers/net/ethernet/intel/e100.c > @@ -2841,7 +2841,7 @@ static int e100_probe(struct pci_dev *pdev, const struct pci_device_id *ent) > netdev->netdev_ops = &e100_netdev_ops; > netdev->ethtool_ops = &e100_ethtool_ops; > netdev->watchdog_timeo = E100_WATCHDOG_PERIOD; > - strncpy(netdev->name, pci_name(pdev), sizeof(netdev->name) - 1); > + strscpy(netdev->name, pci_name(pdev), sizeof(netdev->name)); > > nic = netdev_priv(netdev); > netif_napi_add_weight(netdev, &nic->napi, e100_poll, E100_NAPI_WEIGHT); > > --- > base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 > change-id: 20231009-strncpy-drivers-net-ethernet-intel-e100-c-4547179d9f2c > > 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/