From patchwork Sun May 17 17:29:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11554223 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 6741490 for ; Sun, 17 May 2020 17:32:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 49F8E20810 for ; Sun, 17 May 2020 17:32:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589736731; bh=RHgVpYE0WH0sv+hQelqIqq0LxK+4GDd/mUHkbhjDXU0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bJ/hlQLdkyG6UFO3YUIbcmjDXM3V7GJrJVHRjH+KdSW8ciktvqBZAf0K0KLa4OnxK 1YQd+WUtYE72kogw3hUUxr/9Ud3vBW8IWL+gnGtpTR4V/oMFNoQVsLfl8H0dx4DXfr LvChHBdE5ooUBS1DTV5hPrfTGdKTaxA1NHOG9PEM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726341AbgEQRcL (ORCPT ); Sun, 17 May 2020 13:32:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:51328 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726362AbgEQRcK (ORCPT ); Sun, 17 May 2020 13:32:10 -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 65D9E207E8; Sun, 17 May 2020 17:32:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589736730; bh=RHgVpYE0WH0sv+hQelqIqq0LxK+4GDd/mUHkbhjDXU0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=k51yluV1qBu3Gdfc+RtAJ1VvUC9qoqWym1plGPKSRVJSsmfGRIu2NfOfegoFosLKB s0+MIXHU2MJli8hE4KbOfDM84jnLa+59Ky1EGheI8ECCVCxTR0g0yI2n9dQqPVOX/E 1AElcMo8NTOxzIDilAl8i+s6kavYpU7EppE4J4x8= From: jic23@kernel.org To: linux-iio@vger.kernel.org Cc: Jonathan Cameron , Lars-Peter Clausen Subject: [PATCH 04/11] iio:accel:mma7455: Fix timestamp alignment and prevent data leak. Date: Sun, 17 May 2020 18:29:53 +0100 Message-Id: <20200517173000.220819-5-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: 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 8b5a6aff9bf4..b48caece170e 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; + } 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: