From patchwork Sun Jun 7 15:53:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11591687 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 5A6F0912 for ; Sun, 7 Jun 2020 15:56:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3BC33207ED for ; Sun, 7 Jun 2020 15:56:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545395; bh=nJDWVOzM0afylRhWaEUTTdsW0SwOaqzkiktGFmVbPwA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FIfKOddIn0b/CRybAk11Of7CNn5gjiJxPnw0t8AteehmtERt7o2PkSTF+ubLZEwxz xOl876G6Nfj+KnLaXO28VpBJNGmNodHXG65xicp1BhejxT0IlLuptSu8cnBGGyWE25 hvIuJDR4lydD5qYNkt/8yyv2NtVAy8GmoqTw60oI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726715AbgFGP4e (ORCPT ); Sun, 7 Jun 2020 11:56:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:57428 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726703AbgFGP4e (ORCPT ); Sun, 7 Jun 2020 11:56:34 -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 6CE212078C; Sun, 7 Jun 2020 15:56:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545393; bh=nJDWVOzM0afylRhWaEUTTdsW0SwOaqzkiktGFmVbPwA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ocLHgJae/igYvzPUz5hm/FBA3ZAf3YqPqI2c35+W17jFkjXyAJc/EvrKnGenXWsqC aE5um6V7KMeUfNbNGHIcrW32U9c1zc8WoJYSz8l4P5sVpbGX6wLtMtkrrNWpa6qXan J9woQMqFv4VWANOrcurkI5p/abRpdtkOu7n62vbM= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Lars-Peter Clausen , Gregor Boirie , Linus Walleij Subject: [PATCH 14/32] iio:magnetometer:ak8975 Fix alignment and data leak issues. Date: Sun, 7 Jun 2020 16:53:50 +0100 Message-Id: <20200607155408.958437-15-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 an array of smaller elements 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. This data is allocated with kzalloc so no data can leak apart from previous readings. The explicit alignment of ts is not necessary in this case as by coincidence the padding will end up the same, however I consider it to make the code less fragile and have included it. Fixes: bc11ca4a0b84 ("iio:magnetometer:ak8975: triggered buffer support") Reported-by: Lars-Peter Clausen Cc: Gregor Boirie Cc: Andy Shevchenko Cc: Linus Walleij Signed-off-by: Jonathan Cameron --- drivers/iio/magnetometer/ak8975.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c index 03d71f796177..14d66fd11aa3 100644 --- a/drivers/iio/magnetometer/ak8975.c +++ b/drivers/iio/magnetometer/ak8975.c @@ -366,6 +366,12 @@ struct ak8975_data { struct iio_mount_matrix orientation; struct regulator *vdd; struct regulator *vid; + + /* Ensure natural alignment of timestamp */ + struct { + s16 channels[3]; + s64 ts __aligned(8); + } scan; }; /* Enable attached power regulator if any. */ @@ -793,7 +799,6 @@ static void ak8975_fill_buffer(struct iio_dev *indio_dev) const struct i2c_client *client = data->client; const struct ak_def *def = data->def; int ret; - s16 buff[8]; /* 3 x 16 bits axis values + 1 aligned 64 bits timestamp */ __le16 fval[3]; mutex_lock(&data->lock); @@ -816,11 +821,14 @@ static void ak8975_fill_buffer(struct iio_dev *indio_dev) mutex_unlock(&data->lock); /* Clamp to valid range. */ - buff[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range); - buff[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range); - buff[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range); - - iio_push_to_buffers_with_timestamp(indio_dev, buff, + data->scan.channels[0] = + clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range); + data->scan.channels[1] = + clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range); + data->scan.channels[2] = + clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range); + + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev)); return;