From patchwork Sun May 17 17:29:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11554219 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 F157E913 for ; Sun, 17 May 2020 17:32:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D35CF2067D for ; Sun, 17 May 2020 17:32:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589736730; bh=NiZEO/LT9+bk7JD9gP6ufZO1nUkn5GdrFt7XQqd370s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kwTM7uYxSwPhdT77UqguCvlTV75RtGFE8yXwtk3a0Kj2lVTCMg25yTQXwkMhxJVD0 zFq9GPIvPkrTvM2xGcZOwJO2BThjf7W5r2QpfGPvFDC676jwPMDsl18PnXEKEt50f6 vJuso0qD7KVZdvdat99gTrOqdGfObGsGGznqCaDs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726374AbgEQRcK (ORCPT ); Sun, 17 May 2020 13:32:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:51270 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726276AbgEQRcI (ORCPT ); Sun, 17 May 2020 13:32:08 -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 D924A207ED; Sun, 17 May 2020 17:32:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589736727; bh=NiZEO/LT9+bk7JD9gP6ufZO1nUkn5GdrFt7XQqd370s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HVgTy8bqd9K6mPqaVmkD5LtPoXu5CfzGbh7PwedWBa6AkO5khiOMsDLJ5ITL3jmJ8 ZGgJ4MTPARzzd0FJyAH//F+0S60up18p/5mBeFF8BeXncGrMQMusVWI8bN1HsWLWtY DpqUf+lMVK3JGEhrs4IyCdIex89fWug8VOqL14E4= From: jic23@kernel.org To: linux-iio@vger.kernel.org Cc: Jonathan Cameron , Lars-Peter Clausen , Peter Meerwald Subject: [PATCH 02/11] iio:accel:mma8452: Fix timestamp alignment and prevent data leak. Date: Sun, 17 May 2020 18:29:51 +0100 Message-Id: <20200517173000.220819-3-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 16 byte u8 array 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 ensured by use of an explicit c structure. This data is allocated with kzalloc so no data can leak appart from previous readings. Fixes: c7eeea93ac60 ("iio: Add Freescale MMA8452Q 3-axis accelerometer driver") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron Cc: Peter Meerwald --- drivers/iio/accel/mma8452.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c index 00e100fc845a..704867ffda7a 100644 --- a/drivers/iio/accel/mma8452.c +++ b/drivers/iio/accel/mma8452.c @@ -110,6 +110,12 @@ struct mma8452_data { int sleep_val; struct regulator *vdd_reg; struct regulator *vddio_reg; + + /* Ensure correct alignment of time stamp when present */ + struct { + __be16 channels[3]; + s64 ts; + } buffer; }; /** @@ -1091,14 +1097,13 @@ static irqreturn_t mma8452_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct mma8452_data *data = iio_priv(indio_dev); - u8 buffer[16]; /* 3 16-bit channels + padding + ts */ int ret; - ret = mma8452_read(data, (__be16 *)buffer); + ret = mma8452_read(data, data->buffer.channels); if (ret < 0) goto done; - iio_push_to_buffers_with_timestamp(indio_dev, buffer, + iio_push_to_buffers_with_timestamp(indio_dev, &data->buffer, iio_get_time_ns(indio_dev)); done: