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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 66ECEC433DF for ; Thu, 21 May 2020 19:06:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 42B3120738 for ; Thu, 21 May 2020 19:06:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="hIeY3eXo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729555AbgEUTGL (ORCPT ); Thu, 21 May 2020 15:06:11 -0400 Received: from lelv0142.ext.ti.com ([198.47.23.249]:37456 "EHLO lelv0142.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729548AbgEUTGL (ORCPT ); Thu, 21 May 2020 15:06:11 -0400 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id 04LJ5dE7037142; Thu, 21 May 2020 14:05:39 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1590087939; bh=IM3wnX+hifg+zrZeZXs8VBdhLfgueTxNx5emj0mKCcA=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=hIeY3eXoFNgwQc7m1V62ZWVFsl3azwGeDLwJtrKZSsfqd7JxvJzN20W4MUIso1JEo fP0kl1P37rx9KlXZqsVsTbdmLPFeOratQvTrEHhGEneLuWvnid/PiFwt4oOvnviRDK RjBbsqtbWz8DhPe9GrxSEkw2+Siy4B/Rcy3eRuW4= Received: from DFLE111.ent.ti.com (dfle111.ent.ti.com [10.64.6.32]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 04LJ5dga065976 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 21 May 2020 14:05:39 -0500 Received: from DFLE113.ent.ti.com (10.64.6.34) by DFLE111.ent.ti.com (10.64.6.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3; Thu, 21 May 2020 14:05:38 -0500 Received: from fllv0039.itg.ti.com (10.64.41.19) by DFLE113.ent.ti.com (10.64.6.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3 via Frontend Transport; Thu, 21 May 2020 14:05:38 -0500 Received: from [10.250.38.163] (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id 04LJ5bQr089119; Thu, 21 May 2020 14:05:38 -0500 Subject: Re: [PATCH 07/11] iio:health:afe4403 Fix timestamp alignment and prevent data leak. To: Jonathan Cameron , CC: Jonathan Cameron , Lars-Peter Clausen 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> From: "Andrew F. Davis" Message-ID: Date: Thu, 21 May 2020 15:05:37 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200521194530.08706fee@archlinux> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org 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, > > 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); >>>>>> >>>>>> >>>> >> >