From patchwork Sun Jun 7 15:53:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11591685 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 7496D912 for ; Sun, 7 Jun 2020 15:56:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CDA3207D8 for ; Sun, 7 Jun 2020 15:56:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545393; bh=0kB/tB6TPZqTzGb6+NEUJ5B+RCiWr3Z2M0u4dfsTbj0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NJthkLmDIqcfLvjpau2aaPjQXFh0ADYbhlXNDf7aUs2Zlw0+Md1R7LD3Oc05o0XdH l2OhxIIw9l246pHdSR3S3ZIRmWUDgZ1R2AgvzKNB6KZFe9S5G2hXZdP9XILbWngFlW WKFQUFdxkKTNvG7EQpP45+1W0XjI3wvz+AJYYkxU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726714AbgFGP4c (ORCPT ); Sun, 7 Jun 2020 11:56:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:57410 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726703AbgFGP4c (ORCPT ); Sun, 7 Jun 2020 11:56:32 -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 1014120748; Sun, 7 Jun 2020 15:56:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545392; bh=0kB/tB6TPZqTzGb6+NEUJ5B+RCiWr3Z2M0u4dfsTbj0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sp1DMWVcQlr/0dvTM4wPmUolljL1VwYBqvigPOtOu20fpzZ3ZEARyx/otikyuK8n6 NosX5YKxhulCfsr734f1SMVSxSQG0X7F+3FVVWM1XTXtBStavuuDlUSB/LibbxUIGp xTB2K8ULa1wAQ7QvP2M+rdWw+dNhIKPm1OvRjUiw= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Lars-Peter Clausen , Linus Walleij Subject: [PATCH 13/32] iio:magnetometer:ak8974: Fix alignment and data leak issues Date: Sun, 7 Jun 2020 16:53:49 +0100 Message-Id: <20200607155408.958437-14-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 appart from previous readings. Fixes: 7c94a8b2ee8cf ("iio: magn: add a driver for AK8974") Reported-by: Lars-Peter Clausen Reviewed-by: Linus Walleij Signed-off-by: Jonathan Cameron --- drivers/iio/magnetometer/ak8974.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/iio/magnetometer/ak8974.c b/drivers/iio/magnetometer/ak8974.c index c2260c84f7f1..ea09b549ec4e 100644 --- a/drivers/iio/magnetometer/ak8974.c +++ b/drivers/iio/magnetometer/ak8974.c @@ -192,6 +192,11 @@ struct ak8974 { bool drdy_irq; struct completion drdy_complete; bool drdy_active_low; + /* Ensure timestamp is naturally aligned */ + struct { + __le16 channels[3]; + s64 ts __aligned(8); + } scan; }; static const char ak8974_reg_avdd[] = "avdd"; @@ -657,7 +662,6 @@ static void ak8974_fill_buffer(struct iio_dev *indio_dev) { struct ak8974 *ak8974 = iio_priv(indio_dev); int ret; - __le16 hw_values[8]; /* Three axes + 64bit padding */ pm_runtime_get_sync(&ak8974->i2c->dev); mutex_lock(&ak8974->lock); @@ -667,13 +671,13 @@ static void ak8974_fill_buffer(struct iio_dev *indio_dev) dev_err(&ak8974->i2c->dev, "error triggering measure\n"); goto out_unlock; } - ret = ak8974_getresult(ak8974, hw_values); + ret = ak8974_getresult(ak8974, ak8974->scan.channels); if (ret) { dev_err(&ak8974->i2c->dev, "error getting measures\n"); goto out_unlock; } - iio_push_to_buffers_with_timestamp(indio_dev, hw_values, + iio_push_to_buffers_with_timestamp(indio_dev, &ak8974->scan, iio_get_time_ns(indio_dev)); out_unlock: