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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 22987C433DF for ; Tue, 26 May 2020 16:53:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 05902207FB for ; Tue, 26 May 2020 16:53:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728561AbgEZQx6 (ORCPT ); Tue, 26 May 2020 12:53:58 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2245 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728501AbgEZQx6 (ORCPT ); Tue, 26 May 2020 12:53:58 -0400 Received: from lhreml710-chm.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id 79383F4B381DAEB9D85D; Tue, 26 May 2020 17:53:57 +0100 (IST) Received: from localhost (10.47.89.183) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.1913.5; Tue, 26 May 2020 17:53:56 +0100 Date: Tue, 26 May 2020 17:53:26 +0100 From: Jonathan Cameron To: Lorenzo Bianconi CC: Jonathan Cameron , , Lars-Peter Clausen , Lorenzo Bianconi Subject: Re: [PATCH 04/25] iio:light:st_uvis25 Fix timestamp alignment and prevent data leak. Message-ID: <20200526175326.00007712@Huawei.com> In-Reply-To: <20200526075505.GB339643@localhost.localdomain> References: <20200525170628.503283-1-jic23@kernel.org> <20200525170628.503283-5-jic23@kernel.org> <20200526075505.GB339643@localhost.localdomain> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.89.183] X-ClientProxiedBy: lhreml701-chm.china.huawei.com (10.201.108.50) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Tue, 26 May 2020 09:55:05 +0200 Lorenzo Bianconi 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() > > > > This data is allocated with kzalloc so no data can leak apart > > from previous readings. > > > > Fixes: 3025c8688c1e ("iio: light: add support for UVIS25 sensor") > > Reported-by: Lars-Peter Clausen > > Signed-off-by: Jonathan Cameron > > Cc: Lorenzo Bianconi > > Acked-by: Lorenzo Bianconi Unfortunately this is wrong (as Andy Schevchenko pointed out in one of the other patches). On x86_32 s64 is only aligned to 4 bytes so the size of the structure will end up too small for the IIO alignment rules. There will be a v2 once we've figure out the best, consistent solution. Sorry about that! Jonathan > > > --- > > drivers/iio/light/st_uvis25.h | 5 +++++ > > drivers/iio/light/st_uvis25_core.c | 6 +++--- > > 2 files changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/iio/light/st_uvis25.h b/drivers/iio/light/st_uvis25.h > > index 78bc56aad129..f7027e4c4493 100644 > > --- a/drivers/iio/light/st_uvis25.h > > +++ b/drivers/iio/light/st_uvis25.h > > @@ -27,6 +27,11 @@ struct st_uvis25_hw { > > struct iio_trigger *trig; > > bool enabled; > > int irq; > > + /* Ensure timestamp is naturally aligned */ > > + struct { > > + u8 chan; > > + s64 ts; > > + } scan; > > }; > > > > extern const struct dev_pm_ops st_uvis25_pm_ops; > > diff --git a/drivers/iio/light/st_uvis25_core.c b/drivers/iio/light/st_uvis25_core.c > > index d262c254b895..fe1f2dc970c7 100644 > > --- a/drivers/iio/light/st_uvis25_core.c > > +++ b/drivers/iio/light/st_uvis25_core.c > > @@ -234,17 +234,17 @@ static const struct iio_buffer_setup_ops st_uvis25_buffer_ops = { > > > > static irqreturn_t st_uvis25_buffer_handler_thread(int irq, void *p) > > { > > - u8 buffer[ALIGN(sizeof(u8), sizeof(s64)) + sizeof(s64)]; > > struct iio_poll_func *pf = p; > > struct iio_dev *iio_dev = pf->indio_dev; > > struct st_uvis25_hw *hw = iio_priv(iio_dev); > > int err; > > > > - err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, (int *)buffer); > > + err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, > > + (unsigned int *)&hw->scan.chan); > > if (err < 0) > > goto out; > > > > - iio_push_to_buffers_with_timestamp(iio_dev, buffer, > > + iio_push_to_buffers_with_timestamp(iio_dev, &hw->scan, > > iio_get_time_ns(iio_dev)); > > > > out: > > -- > > 2.26.2 > > >