From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.7]) (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 B1BF61A2C04; Wed, 16 Sep 2026 14:39:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789569554; cv=none; b=uDxOeAR4+BZ/epIhlk+1jnhC5Tgb+lui75JcBDXet9kPnKhmRAEn+GlD58/10yOAQqwLpAbQQrzSIkduLi9PdskUCZiVQZXpEnmnSPFjRhBwd1AVTX9cSdKm+WYnbtycV38yX9TrIG0Bry1wjDHeM3YQFb5eymGZX2Mq/O3i4Ls= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789569554; c=relaxed/simple; bh=XrmV5AYtnPtVAHzQnffCQxg/8kqWWYTjiNeJHagDZwA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UXIVawgHc5j4ms6ohTarAgiLNAKvZwAda3AdZqJBDOTEyXFJTV6BspLPA7Y8dbL/60CkgyJeLcFGkhFjE1gQ5cm2tsCKUOX+eWUzHDO9BRDPIwFiFfTn9e56/Q7Q2QAXBPpmLJzLQpPesn5RIFeMmwZp2XvUNM7bHqpsokIqsWQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=D6CFO0S1; arc=none smtp.client-ip=192.198.163.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="D6CFO0S1" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1789569552; x=1821105552; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=XrmV5AYtnPtVAHzQnffCQxg/8kqWWYTjiNeJHagDZwA=; b=D6CFO0S1w+nn0EgQ/98MN60pbVFmLwYXLXQIaz1OqGiKDNEyU+fDTfjR THotq6gTlNha3qwi4g5yt3IHYuVUnRBHGIDUVZD0ABSO+Y1Cd5nEqq5lg UWhR33O7o4lRcAlAErrUhr5ukGu55oJqr6bUCKlCbsrI7zBxIzOZzlIQf itu+5ZJLNDszmX9E/gZUOU9MEOhP3LXO7la9B8l3kXLipijMdqKt+fls8 QuPk/yYyIvtJTY91pxWqH0j+LSxVPsyQk9gC2LJIGeQ853sIobsE0QiQd jkag1GA+zfF1XJMvw03oIU7mPXQNsFBc0RVZImn3kKktut48Z3mc1TQiE A==; X-CSE-ConnectionGUID: 6mWlzFzuSxiNLC7pUq3ztg== X-CSE-MsgGUID: gBaOFpSZTPSeB0UWbgBOCw== X-IronPort-AV: E=McAfee;i="6800,10657,11905"; a="115483549" X-IronPort-AV: E=Sophos;i="6.27,103,1787036400"; d="scan'208";a="115483549" Received: from fmviesa010.fm.intel.com ([10.60.135.150]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2026 07:39:11 -0700 X-CSE-ConnectionGUID: FstFep20SDOsQTM+1NaYBw== X-CSE-MsgGUID: qK+yDxxsQBWJyllQdob0Ww== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,103,1787036400"; d="scan'208";a="269657357" Received: from ettammin-mobl2.ger.corp.intel.com (HELO localhost) ([10.245.244.145]) by fmviesa010-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2026 07:39:07 -0700 Date: Wed, 16 Sep 2026 17:39:05 +0300 From: Andy Shevchenko To: Fabrice Gasnier Cc: Jonathan Cameron , David Lechner , Nuno =?iso-8859-1?Q?S=E1?= , Andy Shevchenko , Maxime Coquelin , Alexandre Torgue , Olivier Moysan , linux-iio@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sashiko , stable@vger.kernel.org Subject: Re: [PATCH v2] iio: adc: stm32-adc: fix possible division by zero in processed channel Message-ID: References: <20260916-adc-fix-div0-v2-1-f702d3ed782c@foss.st.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260916-adc-fix-div0-v2-1-f702d3ed782c@foss.st.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Wed, Sep 16, 2026 at 04:10:05PM +0200, Fabrice Gasnier wrote: > In case the conversion has failed or returned zero, processing *val > can lead to a division by zero. Need to check for errors, or converted > value is zero, before processing the data. In case the converted value > is zero, e.g. the Vrefint channel, this should be considered as invalid > in all cases. ... > Reported-by: Sashiko > Link: https://lore.kernel.org/all/20260911161555.244F31F000FF@smtp.kernel.org/ Closes: ^^^ > + if (mask == IIO_CHAN_INFO_PROCESSED) { > + int vrefint_raw; > + > + if (ret < 0) { > + iio_device_release_direct(indio_dev); > + return ret; > + } > + > + vrefint_raw = *val; > + Unneeded blank line. > + if (vrefint_raw == 0) { > + iio_device_release_direct(indio_dev); > + return -EINVAL; > + } > + > + *val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / vrefint_raw; > + } Let's look at the current code in this switch-case case IIO_CHAN_INFO_PROCESSED: if (!iio_device_claim_direct(indio_dev)) return -EBUSY; if (chan->type == IIO_VOLTAGE) ret = stm32_adc_single_conv(indio_dev, chan, val); else ret = -EINVAL; if (mask == IIO_CHAN_INFO_PROCESSED) *val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val; iio_device_release_direct(indio_dev); return ret; In the previous version you were trying to keep goto-less approach. However in the current state of affairs I don't think the goto is too bad (after all we need to backport this to the kernels that may not have IIO_DEV_ACQUIRE_DIRECT_MODE() macro). Also checking 'ret' under another condition seems unusual. What about case IIO_CHAN_INFO_PROCESSED: if (!iio_device_claim_direct(indio_dev)) return -EBUSY; if (chan->type == IIO_VOLTAGE) ret = stm32_adc_single_conv(indio_dev, chan, val); else ret = -EINVAL; iio_device_release_direct(indio_dev); if (ret) return ret; if (*val == 0) return -EINVAL; if (mask == IIO_CHAN_INFO_PROCESSED) *val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val; return 0; ? (Yes, we leave that line untouched, but we get the change cleaner.) -- With Best Regards, Andy Shevchenko