From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C635626281 for ; Thu, 5 Oct 2023 14:02:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ER3vAkdF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5BDEC43215; Thu, 5 Oct 2023 14:02:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696514554; bh=Yym/0Ckebdzm9KAQ3LjZwwE9ndHEvxXkPTtFfyHgzvE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ER3vAkdFfURm/ku44XkFaBj8mcSYJLYFIYPR8MrjZrUJHY3tihb1iK/Bz/mNn5mJX nqafOXXXRV/PZt8t2NgzI/Kdq3BZIsN9QCNi5Gdy+6eXj0uTql3Cn6PLdrt8hky8md ozSiQcR+qZRxEJWWYd1Baedcigz67LabOdu7W4mm0UQV5M6dhp111qJ4M7y3fODTfk V4sR7fedFXtIjsCvaM5S+R9s7HSQthyB8cVFHA48Jyg1elyf9RoT4FQOca2mibPYdt SN4tvojfOQ4tWW81z9o1Ues63Mc8ksEvPQjebNgHEicof6x7R3Iiir30sCJ6gwaD+7 5ps5SdnvV4MhQ== Date: Thu, 5 Oct 2023 15:02:38 +0100 From: Jonathan Cameron To: Kees Cook Cc: Justin Stitt , Lars-Peter Clausen , Maxime Coquelin , Alexandre Torgue , linux-iio@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] iio: adc: stm32-adc: replace deprecated strncpy Message-ID: <20231005150238.0f5ff100@jic23-huawei> In-Reply-To: <202309301056.5A21C37D5@keescook> References: <20230921-strncpy-drivers-iio-adc-stm32-adc-c-v1-1-c50eca098597@google.com> <202309232006.690F89A@keescook> <20230930184118.73d7465a@jic23-huawei> <202309301056.5A21C37D5@keescook> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sat, 30 Sep 2023 10:57:03 -0700 Kees Cook wrote: > On Sat, Sep 30, 2023 at 06:41:18PM +0100, Jonathan Cameron wrote: > > On Sat, 23 Sep 2023 20:15:09 -0700 > > Kees Cook wrote: > > > > > On Thu, Sep 21, 2023 at 04:54:00AM +0000, Justin Stitt wrote: > > > > `strncpy` is deprecated for use on NUL-terminated destination strings [1]. > > > > > > > > We should prefer more robust and less ambiguous string interfaces. > > > > > > > > We expect adc->chan_name[val] to be NUL-terminated based on ch_name's > > > > use within functions that expect NUL-terminated strings like strncmp and > > > > printf-likes: > > > > | if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) { > > > > | /* Check internal channel availability */ > > > > | switch (i) { > > > > | case STM32_ADC_INT_CH_VDDCORE: > > > > | if (!adc->cfg->regs->or_vddcore.reg) > > > > | dev_warn(&indio_dev->dev, > > > > | "%s channel not available\n", ch_name); > > > > ... > > > > > > > > There is no evidence that NUL-padding is needed either. > > > > > > Agreed -- it's used as a C string everywhere I can see. > > > > > > > > > > > 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. If, for any reason, NUL-padding _is_ > > > > required we should go for `strscpy_pad`. > > > > > > > > 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 > > > > --- > > > > drivers/iio/adc/stm32-adc.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c > > > > index f7613efb870d..9cdcf396d901 100644 > > > > --- a/drivers/iio/adc/stm32-adc.c > > > > +++ b/drivers/iio/adc/stm32-adc.c > > > > @@ -2209,7 +2209,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev, > > > > ret = -EINVAL; > > > > goto err; > > > > } > > > > - strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ); > > > > + strscpy(adc->chan_name[val], name, STM32_ADC_CH_SZ); > > > > > > I still prefer sizeof($dst), but yes, these are the same: > > > > > > char chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ]; > > > > > > If this needs a v2, please improve the Subject, but it is technically > > > correct, so: > > > > Hi Kees, > > > > I can tweak the subject whilst applying. What did you have in mind > > as a better one? > > I would use "iio: adc: stm32-adc: Replace deprecated strncpy() with strscpy()" Makes sense. I also used the () approach to identify functions in the text of the patch description instead of `funcname` Applied with those tweaks to the togreg branch of iio.git but initially just pushed out as testing to let 0-day take a look at it. Thanks, Jonathan > > Thanks! > > -Kees >