From patchwork Sun Jun 7 15:53:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11591667 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 7CAAD913 for ; Sun, 7 Jun 2020 15:56:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6564C20659 for ; Sun, 7 Jun 2020 15:56:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545381; bh=c5onn80lT01q31EJJU3E2Jx+ZMccZWKb1BdZ3Bnz7dc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Fiv9XVJS12l9RWXTfPlkPaL3WxEinGk9F+NJiR6SRbellUv95zr09l7BL/lreOOQO H4y4xWZ+H9+iOdkFhNZWJvbqN/Be+UTocmlydbIRK8zcn0i+rzWCfwVOToVW/9UFly HAGNdbSeXEnNWhRPblg4itGyiKsBqMOVkK06GpCc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726673AbgFGP4U (ORCPT ); Sun, 7 Jun 2020 11:56:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:57242 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726631AbgFGP4U (ORCPT ); Sun, 7 Jun 2020 11:56:20 -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 40B2C20748; Sun, 7 Jun 2020 15:56:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545380; bh=c5onn80lT01q31EJJU3E2Jx+ZMccZWKb1BdZ3Bnz7dc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0qW42az7+n4gjznyRV41DVjPnAitf747OchBv7qV3bMdsxbV1+UXPi40zxEN8PpuX nWbCX6I0iMfjCOuWpYtXQEd0859hTiy+nNuTdD5C9Ys+Ri7ThBHwOQO706Utyjetjk ixP9fJmyVp1wWYLt4d3fss5U+oGGIWnAo3KvUszU= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Lars-Peter Clausen Subject: [PATCH 04/32] iio:accel:mma7455: Fix timestamp alignment and prevent data leak. Date: Sun, 7 Jun 2020 16:53:40 +0100 Message-Id: <20200607155408.958437-5-jic23@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200607155408.958437-1-jic23@kernel.org> References: <20200607155408.958437-1-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. The force alignment of ts is not strictly necessary in this particularly case but does make the code less fragile. Fixes: a84ef0d181d9 ("iio: accel: add Freescale MMA7455L/MMA7456L 3-axis accelerometer driver") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron --- drivers/iio/accel/mma7455_core.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/iio/accel/mma7455_core.c b/drivers/iio/accel/mma7455_core.c index 7e99bcb3398d..922bd38ff6ea 100644 --- a/drivers/iio/accel/mma7455_core.c +++ b/drivers/iio/accel/mma7455_core.c @@ -52,6 +52,14 @@ struct mma7455_data { struct regmap *regmap; + /* + * Used to reorganize data. Will ensure correct alignment of + * the timestamp if present + */ + struct { + __le16 channels[3]; + s64 ts __aligned(8); + } scan; }; static int mma7455_drdy(struct mma7455_data *mma7455) @@ -82,19 +90,19 @@ static irqreturn_t mma7455_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct mma7455_data *mma7455 = iio_priv(indio_dev); - u8 buf[16]; /* 3 x 16-bit channels + padding + ts */ int ret; ret = mma7455_drdy(mma7455); if (ret) goto done; - ret = regmap_bulk_read(mma7455->regmap, MMA7455_REG_XOUTL, buf, - sizeof(__le16) * 3); + ret = regmap_bulk_read(mma7455->regmap, MMA7455_REG_XOUTL, + mma7455->scan.channels, + sizeof(mma7455->scan.channels)); if (ret) goto done; - iio_push_to_buffers_with_timestamp(indio_dev, buf, + iio_push_to_buffers_with_timestamp(indio_dev, &mma7455->scan, iio_get_time_ns(indio_dev)); done: