From patchwork Wed Jul 22 15:50:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11678699 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 7BF8C14E3 for ; Wed, 22 Jul 2020 15:53:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 633402080D for ; Wed, 22 Jul 2020 15:53:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433195; bh=JPjPQTwurZOmRt6qpeWPLAIdDax89TZBB7giNHldGRQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gw20CJXxAf1uD5iAYuWC5Htgfy6ZAWwNcHOFUq5yk4tFImLiqy8Kp4+xvLdJXncrg ULR27DHjMpyWjTJq4j2hsRN3cfg4/o2VFlI2TifvgnhHF3ETktDHv1auZBeipow6Cg sLyO4/BygFAJAIhNtVInjKpqkAfjR+83bokQSn9E= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727985AbgGVPxP (ORCPT ); Wed, 22 Jul 2020 11:53:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:35554 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxO (ORCPT ); Wed, 22 Jul 2020 11:53:14 -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 6E18C207DD; Wed, 22 Jul 2020 15:53:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433194; bh=JPjPQTwurZOmRt6qpeWPLAIdDax89TZBB7giNHldGRQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D64YmlOreutlTCHiIY6pWAweLbo9Yw3fefHZ7sCqC2dAfx2Dixsp5UM7kjjC7HFFn 2hOq/pE5UyBs8ryXNnRakcYl8H4sqB86aG05aogmILeXIfdnsF0b184tHcWdtXax7B JMDwVWH8e2VeHbAXbOdzYQ6R4NgFKsdkSJf8HWtw= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron Subject: [PATCH v3 04/27] iio:accel:mma7455: Fix timestamp alignment and prevent data leak. Date: Wed, 22 Jul 2020 16:50:40 +0100 Message-Id: <20200722155103.979802-5-jic23@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200722155103.979802-1-jic23@kernel.org> References: <20200722155103.979802-1-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: