From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2333C433DF for ; Sun, 9 Aug 2020 17:23:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 90211206CD for ; Sun, 9 Aug 2020 17:23:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596993826; bh=t2sSXxwpFTMr2SBhWHsJ4cMFRH5RmX5naU4PRaPpQK4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=PskrUdGEjHpcm12sbj1mx90Oggz1n1gIlGQne3kzkwqHfUKVU5vjXMD9sN0TDigjW rdqFpy2hfOlYs515fPHBemnaKB+aaLuhNURS/kOjIKvNOeIqXfcZD71yqrsvWWDjz6 NgyOCu8WiYjWpZRtM2uto5Y/SKF+KY2uYhidqBjg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726289AbgHIRXq (ORCPT ); Sun, 9 Aug 2020 13:23:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:54764 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726236AbgHIRXq (ORCPT ); Sun, 9 Aug 2020 13:23:46 -0400 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2D132206C3; Sun, 9 Aug 2020 17:23:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596993825; bh=t2sSXxwpFTMr2SBhWHsJ4cMFRH5RmX5naU4PRaPpQK4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ghmkzRT29r1dnJ9/RYOGnu39lDPoqEUDev8DxbtPcxoJ38ZoiibyPP1tW2sl4GjjL ymmFkwkDFER+pI86y5p/OKRWnS4ctrXiqbTWLyXxMGMlpJwQ5GBw3iS6G8trjIrOCw 2MAWg6SRS/SsQmr/PyzOKpDv9gOx9UxOUxBdfEjc= Date: Sun, 9 Aug 2020 18:23:41 +0100 From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Narcisa Ana Maria Vasile Subject: Re: [PATCH v3 07/27] iio:chemical:ccs811: Fix timestamp alignment and prevent data leak. Message-ID: <20200809182341.5ceadf51@archlinux> In-Reply-To: <20200722155103.979802-8-jic23@kernel.org> References: <20200722155103.979802-1-jic23@kernel.org> <20200722155103.979802-8-jic23@kernel.org> X-Mailer: Claws Mail 3.17.6 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Wed, 22 Jul 2020 16:50:43 +0100 Jonathan Cameron wrote: > From: Jonathan Cameron > > One of a class of bugs pointed out by Lars in a recent review. > iio_push_to_buffers_with_timestamp assumes the buffer used is aligned > to the size of the timestamp (8 bytes). This is not guaranteed in > this driver which uses an array of smaller elements on the stack. > As Lars also noted this anti pattern can involve a leak of data to > userspace and that indeed can happen here. We close both issues by > moving to a suitable structure in the iio_priv() data with alignment > explicitly requested. This data is allocated with kzalloc so no > data can leak appart from previous readings. > > The explicit alignment of ts is necessary to ensure consistent > padding for x86_32 in which the ts would otherwise be 4 byte aligned. > > Fixes: 283d26917ad6 ("iio: chemical: ccs811: Add triggered buffer support") > Reported-by: Lars-Peter Clausen > Cc: Narcisa Ana Maria Vasile > Signed-off-by: Jonathan Cameron Applied > --- > drivers/iio/chemical/ccs811.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c > index 2b007e7568b2..60dd87e96f5f 100644 > --- a/drivers/iio/chemical/ccs811.c > +++ b/drivers/iio/chemical/ccs811.c > @@ -78,6 +78,11 @@ struct ccs811_data { > struct iio_trigger *drdy_trig; > struct gpio_desc *wakeup_gpio; > bool drdy_trig_on; > + /* Ensures correct alignment of timestamp if present */ > + struct { > + s16 channels[2]; > + s64 ts __aligned(8); > + } scan; > }; > > static const struct iio_chan_spec ccs811_channels[] = { > @@ -327,17 +332,17 @@ static irqreturn_t ccs811_trigger_handler(int irq, void *p) > struct iio_dev *indio_dev = pf->indio_dev; > struct ccs811_data *data = iio_priv(indio_dev); > struct i2c_client *client = data->client; > - s16 buf[8]; /* s16 eCO2 + s16 TVOC + padding + 8 byte timestamp */ > int ret; > > - ret = i2c_smbus_read_i2c_block_data(client, CCS811_ALG_RESULT_DATA, 4, > - (u8 *)&buf); > + ret = i2c_smbus_read_i2c_block_data(client, CCS811_ALG_RESULT_DATA, > + sizeof(data->scan.channels), > + (u8 *)data->scan.channels); > if (ret != 4) { > dev_err(&client->dev, "cannot read sensor data\n"); > goto err; > } > > - iio_push_to_buffers_with_timestamp(indio_dev, buf, > + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, > iio_get_time_ns(indio_dev)); > > err: