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 D20FDC433E0 for ; Sun, 9 Aug 2020 17:19:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE052206CD for ; Sun, 9 Aug 2020 17:19:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596993556; bh=olWeJly2HPDWBriIy6/DVC8IOzx8aABeMJvXj+QWv6w=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=Rdy6cx7l9c2YIGOHKYi9E20Jb93rXOCJEFl9NjPlG4jCL84V+/RepRZeg2/AMBZta mOhQ4ZcF58Ibqam+04YdVozSGcilazyyIxvvsqAvptS3np3t309DVdQkx2koDi4PgB aZK3Dhc6io2UF06PMIw+byseR2ac4pjSKEUtvaTo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726229AbgHIRTQ (ORCPT ); Sun, 9 Aug 2020 13:19:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:54244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726175AbgHIRTQ (ORCPT ); Sun, 9 Aug 2020 13:19:16 -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 8B77B206C3; Sun, 9 Aug 2020 17:19:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596993555; bh=olWeJly2HPDWBriIy6/DVC8IOzx8aABeMJvXj+QWv6w=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=sj3a3UTNWpSNymRgkOfNa2fdu8cz+jF1VcPZPFygIU8VXXC9dEcHQNZ02ggFT1Brz Yh7UvQtKI4FdQjd11XPHXmN13yMzyPdxIcVBJc7j5dTA+DYajJ/AOVykzxEbKPODkt OxmSt2zY8HcwIqWsP0bfb+Rkb+ZWgFhnF5I+hmls= Date: Sun, 9 Aug 2020 18:19:12 +0100 From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron Subject: Re: [PATCH v3 04/27] iio:accel:mma7455: Fix timestamp alignment and prevent data leak. Message-ID: <20200809181912.59839046@archlinux> In-Reply-To: <20200722155103.979802-5-jic23@kernel.org> References: <20200722155103.979802-1-jic23@kernel.org> <20200722155103.979802-5-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 16:50:40 +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 force alignment of ts is not strictly necessary in this particularly > case but does make the code less fragile. > > Fixes: a84ef0d181d9 ("iio: accel: add Freescale MMA7455L/MMA7456L 3-axis accelerometer driver") > Reported-by: Lars-Peter Clausen > Signed-off-by: Jonathan Cameron Applied to the fixes-togreg branch of iio.git and marked for stable. Thanks, Jonathan > --- > drivers/iio/accel/mma7455_core.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/drivers/iio/accel/mma7455_core.c b/drivers/iio/accel/mma7455_core.c > index 7e99bcb3398d..922bd38ff6ea 100644 > --- a/drivers/iio/accel/mma7455_core.c > +++ b/drivers/iio/accel/mma7455_core.c > @@ -52,6 +52,14 @@ > > struct mma7455_data { > struct regmap *regmap; > + /* > + * Used to reorganize data. Will ensure correct alignment of > + * the timestamp if present > + */ > + struct { > + __le16 channels[3]; > + s64 ts __aligned(8); > + } scan; > }; > > static int mma7455_drdy(struct mma7455_data *mma7455) > @@ -82,19 +90,19 @@ static irqreturn_t mma7455_trigger_handler(int irq, void *p) > struct iio_poll_func *pf = p; > struct iio_dev *indio_dev = pf->indio_dev; > struct mma7455_data *mma7455 = iio_priv(indio_dev); > - u8 buf[16]; /* 3 x 16-bit channels + padding + ts */ > int ret; > > ret = mma7455_drdy(mma7455); > if (ret) > goto done; > > - ret = regmap_bulk_read(mma7455->regmap, MMA7455_REG_XOUTL, buf, > - sizeof(__le16) * 3); > + ret = regmap_bulk_read(mma7455->regmap, MMA7455_REG_XOUTL, > + mma7455->scan.channels, > + sizeof(mma7455->scan.channels)); > if (ret) > goto done; > > - iio_push_to_buffers_with_timestamp(indio_dev, buf, > + iio_push_to_buffers_with_timestamp(indio_dev, &mma7455->scan, > iio_get_time_ns(indio_dev)); > > done: