From patchwork Sun May 17 17:29:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11554229 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 142F9913 for ; Sun, 17 May 2020 17:32:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 004C62067D for ; 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=te4lt9SuagOI5X8R2hnGAgrUQqUKRttx/WZsbIr7q2o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Lx7clv2XvC0tV/BEYzfQJ0nIgmCyh0tGuK9s2tB9cn9Q9/6K0z9QjAeQYtNY39QcH TBgswRv6nKeacvVlf9wyvxRx77cjJvtapjyF8te8kpjCMY2jL7wjvhgVHQjr4NLCZR STkCm4psK/KVIfs/7M7l08WJy0RZy9bzeXNsMMI0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726490AbgEQRcO (ORCPT ); Sun, 17 May 2020 13:32:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:51380 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726362AbgEQRcO (ORCPT ); Sun, 17 May 2020 13:32:14 -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 E3F3220810; Sun, 17 May 2020 17:32:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589736733; bh=te4lt9SuagOI5X8R2hnGAgrUQqUKRttx/WZsbIr7q2o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jZpz2DKY+vWx3YWAdw3rYcFc+gZAS7VHcR/Ditq5SiH/TfahJ8NyyGzdrQufjF74i +7LAQTMzPdQap2NPnNRic4zkY681wMzS0/tEF7Wff/9jalO0i03eKOm85EhFhSeOpP prvgD5hr7Vz8bAhtWjN99WavBheQnf7ibaS/x620= From: jic23@kernel.org To: linux-iio@vger.kernel.org Cc: Jonathan Cameron , Lars-Peter Clausen , "Andrew F . Davis" Subject: [PATCH 07/11] iio:health:afe4403 Fix timestamp alignment and prevent data leak. Date: Sun, 17 May 2020 18:29:56 +0100 Message-Id: <20200517173000.220819-8-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 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 Acked-by: 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); }; 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);