From patchwork Sun Jun 7 15:53:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11591663 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 CB1BF912 for ; Sun, 7 Jun 2020 15:56:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A3DD82075A for ; Sun, 7 Jun 2020 15:56:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545378; bh=rjkMoZ+extP8HeW0stl/HFc3GphsLQokQhYBIPctZwE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Q8PcjxgueCYrZmAP9vbwFm1aRW7mJPokw1iQ792Va5j6zsdPCBn6t/SCLBqP2RSUa ij6koN4eicdJJvUceDKSm+l+/XFWJsjoJhhAE++jU7ZYySfS5ktSh1T4nqyhSZsvYJ wAiPGFv24c8qQ5zZ1sHs2ecXHKuN3+ow3xXiu9Oc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726662AbgFGP4S (ORCPT ); Sun, 7 Jun 2020 11:56:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:57214 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726631AbgFGP4R (ORCPT ); Sun, 7 Jun 2020 11:56:17 -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 75431206F6; Sun, 7 Jun 2020 15:56:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545377; bh=rjkMoZ+extP8HeW0stl/HFc3GphsLQokQhYBIPctZwE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vNn4Oj4vlCHoKlElHFf7stKqE3MbCIzQoCiTEGw7KCYAe19GR37rGf1V8lq1rQ8Wc YZ1wuK/1tO1i1iecKwLvufxUuHKvIrcqN/0O3f53bEe0oRnwUWeZ78eRN+4g3lzQnY bFRStZsBBY0cMUR+76o+SdlJG6P0sBIHV6bW6zDs= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Lars-Peter Clausen , Peter Meerwald Subject: [PATCH 02/32] iio:accel:mma8452: Fix timestamp alignment and prevent data leak. Date: Sun, 7 Jun 2020 16:53:38 +0100 Message-Id: <20200607155408.958437-3-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 additional forcing of the 8 byte alignment of the timestamp is not strictly necessary but makes the code less fragile by making this explicit. Fixes: c7eeea93ac60 ("iio: Add Freescale MMA8452Q 3-axis accelerometer driver") Reported-by: Lars-Peter Clausen Cc: Peter Meerwald Signed-off-by: Jonathan Cameron --- 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 ef3df402fc3c..e58fcc3741c4 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 __aligned(8); + } 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: