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=-8.6 required=3.0 tests=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 3D1D3C433DF for ; Sun, 24 May 2020 15:33:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1AB7A207DA for ; Sun, 24 May 2020 15:33:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590334439; bh=GVY8Kqc55NYrcBz/PcTqRSIfP4aMITUPLaIvqt2hU9E=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=wMaBjpeCodnyPM4n/sq9IrmRZ+kDfMb+jvnASWxObPCPRVkmRbEJ+w0T6XaxEoVgr 9T8sgrrqHEn7ivXQFDHGpjll5b6KhC4NMH05BrdhpwVktFwyp9zxv442tb4BTsO7FG OCRCflAdHQ1bA9e+1KNuD7yVTTeLrRJmnoHQGpH8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726799AbgEXPd6 (ORCPT ); Sun, 24 May 2020 11:33:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:38180 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726506AbgEXPd6 (ORCPT ); Sun, 24 May 2020 11:33:58 -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 445AE207CB; Sun, 24 May 2020 15:33:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590334438; bh=GVY8Kqc55NYrcBz/PcTqRSIfP4aMITUPLaIvqt2hU9E=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=PwMgLdqhEZf/ah3W2tDgNqi+pbwibJ9NnOA85V52lN3pbwMFAXzwVOuvj+OgMmIOL oTwZ3tfRCa/gQ9G1TaHaxPijZ4GfAupN+D3v+EdVpZVjQWDiIPKWesBHB61oo4uvUJ o/jrEssTIILXuJcjGWKWDfaWLaKZrRE4cmgSalW4= Date: Sun, 24 May 2020 16:33:54 +0100 From: Jonathan Cameron To: "Andrew F. Davis" Cc: , Jonathan Cameron , Lars-Peter Clausen Subject: Re: [PATCH 07/11] iio:health:afe4403 Fix timestamp alignment and prevent data leak. Message-ID: <20200524163354.79910d32@archlinux> In-Reply-To: References: <20200517173000.220819-1-jic23@kernel.org> <20200517173000.220819-8-jic23@kernel.org> <951a305b-b3b4-6cfc-f39a-f7458dfcb54b@ti.com> <83B13776-904F-4FCF-93A6-D430281E4B55@jic23.retrosnub.co.uk> <5763033E-38E7-434A-AAA9-E5D27FEDBA35@jic23.retrosnub.co.uk> <20200521194530.08706fee@archlinux> X-Mailer: Claws Mail 3.17.5 (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 Thu, 21 May 2020 15:05:37 -0400 "Andrew F. Davis" wrote: > On 5/21/20 2:45 PM, Jonathan Cameron wrote: > > On Thu, 21 May 2020 15:44:43 +0100 > > Jonathan Cameron wrote: > > > >> On 21 May 2020 14:11:10 BST, "Andrew F. Davis" wrote: > >>> > >>> > >>> On 5/18/20 12:06 PM, Jonathan Cameron wrote: > >>>> > >>>> > >>>> On 18 May 2020 01:09:47 BST, "Andrew F. Davis" wrote: > >>>>> On 5/17/20 1:29 PM, jic23@kernel.org 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 32 byte 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. > >>>>>> > >>>>>> Fixes: eec96d1e2d31 ("iio: health: Add driver for the TI AFE4403 > >>>>> heart monitor") > >>>>>> Reported-by: Lars-Peter Clausen > >>>>>> Signed-off-by: Jonathan Cameron > >>>>>> Cc: Andrew F. Davis > >>>>>> --- > >>>>>> drivers/iio/health/afe4403.c | 9 ++++++--- > >>>>>> 1 file changed, 6 insertions(+), 3 deletions(-) > >>>>>> > >>>>>> diff --git a/drivers/iio/health/afe4403.c > >>>>> b/drivers/iio/health/afe4403.c > >>>>>> index e9f87e42ff4f..a3507624b30f 100644 > >>>>>> --- a/drivers/iio/health/afe4403.c > >>>>>> +++ b/drivers/iio/health/afe4403.c > >>>>>> @@ -65,6 +65,7 @@ static const struct reg_field > >>> afe4403_reg_fields[] > >>>>> = { > >>>>>> * @regulator: Pointer to the regulator for the IC > >>>>>> * @trig: IIO trigger for this device > >>>>>> * @irq: ADC_RDY line interrupt number > >>>>>> + * @buffer: Used to construct data layout to push into IIO buffer. > >>>>>> */ > >>>>>> struct afe4403_data { > >>>>>> struct device *dev; > >>>>>> @@ -74,6 +75,8 @@ struct afe4403_data { > >>>>>> struct regulator *regulator; > >>>>>> struct iio_trigger *trig; > >>>>>> int irq; > >>>>>> + /* Ensure suitable alignment for timestamp */ > >>>>>> + s32 buffer[8] __aligned(8); > >>>>> > >>>>> > >>>>> One of those fancy structs with the timestamp specified would be > >>> nice > >>>>> here like the other patches. IIRC we have 6 s32 channels, plus a s64 > >>>>> ts. > >>>> > >>>> I think we may only have some of those channels enabled. So ts may > >>> be it several > >>>> locations in the buffer. > >>>> > >>> > >>> Might have been better to have the ts at the beginning, could have also > >>> helped with alignment for when an odd number of channels are enabled. > >> > >> Perhaps but for many use cases we don't turn timestamps on and we would need to pad > >> anyway for alignment of the fifo. > >> > >>> > >>>> Hence we could use the structure approach but it might give a false > >>> sense > >>>> of what is going on. > >>>> > >>> > >>> That's true, it can always be cleaned later then. > >> > >> Agreed. This is definitely something we can revisit sometime in the future. > > > > Formal Ack on applying the two afe patches? > > > > Acked-by: Andrew F. Davis Thanks. Applied to the fixes-togreg branch of iio.git and marked for stable. These won't go anywhere now until after the merge window. Thanks, Jonathan > > > Thanks, > > > > Jonathan > >> > >> J > >>> > >>> Andrew > >>> > >>>> J > >>>>> > >>>>> Other than that everything looks good. > >>>>> > >>>>> Andrew > >>>>> > >>>>> > >>>>>> }; > >>>>>> > >>>>>> enum afe4403_chan_id { > >>>>>> @@ -309,7 +312,6 @@ static irqreturn_t afe4403_trigger_handler(int > >>>>> irq, void *private) > >>>>>> struct iio_dev *indio_dev = pf->indio_dev; > >>>>>> struct afe4403_data *afe = iio_priv(indio_dev); > >>>>>> int ret, bit, i = 0; > >>>>>> - s32 buffer[8]; > >>>>>> u8 tx[4] = {AFE440X_CONTROL0, 0x0, 0x0, AFE440X_CONTROL0_READ}; > >>>>>> u8 rx[3]; > >>>>>> > >>>>>> @@ -326,7 +328,7 @@ static irqreturn_t afe4403_trigger_handler(int > >>>>> irq, void *private) > >>>>>> if (ret) > >>>>>> goto err; > >>>>>> > >>>>>> - buffer[i++] = get_unaligned_be24(&rx[0]); > >>>>>> + afe->buffer[i++] = get_unaligned_be24(&rx[0]); > >>>>>> } > >>>>>> > >>>>>> /* Disable reading from the device */ > >>>>>> @@ -335,7 +337,8 @@ static irqreturn_t afe4403_trigger_handler(int > >>>>> irq, void *private) > >>>>>> if (ret) > >>>>>> goto err; > >>>>>> > >>>>>> - iio_push_to_buffers_with_timestamp(indio_dev, buffer, > >>>>> pf->timestamp); > >>>>>> + iio_push_to_buffers_with_timestamp(indio_dev, afe->buffer, > >>>>>> + pf->timestamp); > >>>>>> err: > >>>>>> iio_trigger_notify_done(indio_dev->trig); > >>>>>> > >>>>>> > >>>> > >> > >