From patchwork Sun May 17 17:29:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11554231 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 510EE90 for ; Sun, 17 May 2020 17:32:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3DDB020823 for ; Sun, 17 May 2020 17:32:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589736736; bh=/0GvY/0b4q9Y+cINXq9Ay88qg0135Fkn4WcgkpasOcU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=yHcm/tjgxAtMWvZgRYyLLfoW6DCBDmkX6bVHL8tqS5obqbZYhE7d3d0sQt9dS1sOe FO8sTUeFTjpcsfb91LIXdDkP3Ubr+8qGssl4e2erXZ/JhxKTwsDxMxl07D1Gdrk9Eh RjUEpWy9f/eZk2wsm8EIEtuGKo5JXrWjfdhYaPMI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726492AbgEQRcP (ORCPT ); Sun, 17 May 2020 13:32:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:51390 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726362AbgEQRcP (ORCPT ); Sun, 17 May 2020 13:32:15 -0400 Received: from localhost.localdomain (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3586C2081A; Sun, 17 May 2020 17:32:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589736735; bh=/0GvY/0b4q9Y+cINXq9Ay88qg0135Fkn4WcgkpasOcU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gYIXmQDrH30Ode9btGWhxAMfDBTmeKbYaj0PVMCXNl497uVhP0qxK8hEMEyvEOsPA Swa3q4SI+EIHIGfrdbiFh9Vn1Q7aZoiPpXE7S7oGEqMp5Gjwmon+Ad6LhZuBiCOe85 wA6R6DhOkocddpYloAo+cOrFZIkxmfWOnWYFHwg0= From: jic23@kernel.org To: linux-iio@vger.kernel.org Cc: Jonathan Cameron , Lars-Peter Clausen , "Andrew F . Davis" Subject: [PATCH 08/11] iio:health:afe4404 Fix timestamp alignment and prevent data leak. Date: Sun, 17 May 2020 18:29:57 +0100 Message-Id: <20200517173000.220819-9-jic23@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200517173000.220819-1-jic23@kernel.org> References: <20200517173000.220819-1-jic23@kernel.org> MIME-Version: 1.0 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org 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 40 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: 87aec56e27ef ("iio: health: Add driver for the TI AFE4404 heart monitor") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron Cc: Andrew F. Davis --- drivers/iio/health/afe4404.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/iio/health/afe4404.c b/drivers/iio/health/afe4404.c index e728bbb21ca8..cebb1fd4d0b1 100644 --- a/drivers/iio/health/afe4404.c +++ b/drivers/iio/health/afe4404.c @@ -83,6 +83,7 @@ static const struct reg_field afe4404_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 a scan to push to the iio buffer. */ struct afe4404_data { struct device *dev; @@ -91,6 +92,7 @@ struct afe4404_data { struct regulator *regulator; struct iio_trigger *trig; int irq; + s32 buffer[10] __aligned(8); }; enum afe4404_chan_id { @@ -328,17 +330,17 @@ static irqreturn_t afe4404_trigger_handler(int irq, void *private) struct iio_dev *indio_dev = pf->indio_dev; struct afe4404_data *afe = iio_priv(indio_dev); int ret, bit, i = 0; - s32 buffer[10]; for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) { ret = regmap_read(afe->regmap, afe4404_channel_values[bit], - &buffer[i++]); + &afe->buffer[i++]); 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);