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 53509C433E0 for ; Sun, 9 Aug 2020 17:17:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 311E8206C3 for ; Sun, 9 Aug 2020 17:17:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596993464; bh=uc26ozDmw+sC1xVWwb6POwL36K609S5X/oUFQeNBNjc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=dE+gDifJrAFIUk+/nUBPvk8a3UqntzzBMX/sv4GoNeYKU/9rP4/lL44BO72ozMJQ7 MPtmubGIViEplfoC9zDC92nN+qygb7ZDSm9ErfgK0fiK6Gq+3oXQtWiwWqAFqlhLPb QXr97dKF4QAXeEHxxe2U5muQOEx4uquGOcUArdI8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726321AbgHIRRn (ORCPT ); Sun, 9 Aug 2020 13:17:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:53954 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726175AbgHIRRn (ORCPT ); Sun, 9 Aug 2020 13:17:43 -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 37166206A2; Sun, 9 Aug 2020 17:17:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596993463; bh=uc26ozDmw+sC1xVWwb6POwL36K609S5X/oUFQeNBNjc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=SkyhqvUzjn9U8qm5ZjAKswO1gyFi4lHOCOC8fxhtmWoCqvCgYd6ieverA8QgFPVBD To7nQI4KVUQmL8f79YzKKrIHkc3Adzqy5yPFSla4Ot7Vq6XYZId03OnHbgqb/1z0jE UumkywbUPQVHe5pPaDctREN4lFEaCbNslEml76SY= Date: Sun, 9 Aug 2020 18:14:20 +0100 From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron Subject: Re: [PATCH v3 02/27] iio:accel:mma8452: Fix timestamp alignment and prevent data leak. Message-ID: <20200809181420.337909ec@archlinux> In-Reply-To: <20200722155103.979802-3-jic23@kernel.org> References: <20200722155103.979802-1-jic23@kernel.org> <20200722155103.979802-3-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 16:50:38 +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 a 16 byte u8 array 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 > ensured by use of an explicit c structure. This data is allocated > with kzalloc so no data can leak appart from previous readings. > > The additional forcing of the 8 byte alignment of the timestamp > is not strictly necessary but makes the code less fragile by > making this explicit. > > Fixes: c7eeea93ac60 ("iio: Add Freescale MMA8452Q 3-axis accelerometer driver") > Reported-by: Lars-Peter Clausen > Cc: Peter Meerwald > Signed-off-by: Jonathan Cameron Applied to the fixes-togreg branch of iio.git. Thanks, Jonathan > --- > drivers/iio/accel/mma8452.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c > index ba27f8673131..1cf2b5db26ca 100644 > --- a/drivers/iio/accel/mma8452.c > +++ b/drivers/iio/accel/mma8452.c > @@ -110,6 +110,12 @@ struct mma8452_data { > int sleep_val; > struct regulator *vdd_reg; > struct regulator *vddio_reg; > + > + /* Ensure correct alignment of time stamp when present */ > + struct { > + __be16 channels[3]; > + s64 ts __aligned(8); > + } buffer; > }; > > /** > @@ -1091,14 +1097,13 @@ static irqreturn_t mma8452_trigger_handler(int irq, void *p) > struct iio_poll_func *pf = p; > struct iio_dev *indio_dev = pf->indio_dev; > struct mma8452_data *data = iio_priv(indio_dev); > - u8 buffer[16]; /* 3 16-bit channels + padding + ts */ > int ret; > > - ret = mma8452_read(data, (__be16 *)buffer); > + ret = mma8452_read(data, data->buffer.channels); > if (ret < 0) > goto done; > > - iio_push_to_buffers_with_timestamp(indio_dev, buffer, > + iio_push_to_buffers_with_timestamp(indio_dev, &data->buffer, > iio_get_time_ns(indio_dev)); > > done: