From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6EC3BC433F7 for ; Wed, 22 Jul 2020 15:53:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 48D0F206F5 for ; Wed, 22 Jul 2020 15:53:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433211; bh=ScHk/g2so9KptJyBAfekbi3R35PPSVX+BKTDj1tgQIo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kzEy8yOpPZTxNZwnyeKYQzmiMEt3GPm60507syVwh7H0xFlCEAsE+O/O2bwTIhaRQ OhFIR5OT4H8KJz9WJahhX5Nl9bRiPPloy7DQ+0+464oWanoNoaZ/IH5qBSuyb0S+3r G/U5wZZfZ6/UIZs+DVSSz07TeWHXtP0yu4FtyT1M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729642AbgGVPxa (ORCPT ); Wed, 22 Jul 2020 11:53:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:35712 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxa (ORCPT ); Wed, 22 Jul 2020 11:53:30 -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 92F2720B1F; Wed, 22 Jul 2020 15:53:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433209; bh=ScHk/g2so9KptJyBAfekbi3R35PPSVX+BKTDj1tgQIo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X5XNsDsRbVSOM8l/REPJsjmiI0+w9asSxuE/Sqw7SZvaGd9vTDub+epB6eEuIDkbV JDizWZXjHacqIlrDLOgsCmayVtoiUNhduQelWzkWZEPmIZJt88JMaAn0dHBchvcHQ1 8WCdultNosaMpkF5+huJ7UhI8YjU8eCzeAD0vrVQ= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron Subject: [PATCH v3 14/27] iio:magnetometer:mag3110 Fix alignment and data leak issues. Date: Wed, 22 Jul 2020 16:50:50 +0100 Message-Id: <20200722155103.979802-15-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 Content-Transfer-Encoding: 8bit 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 but does make the code slightly less fragile so I have included it. Fixes: 39631b5f9584 ("iio: Add Freescale mag3110 magnetometer driver") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron --- drivers/iio/magnetometer/mag3110.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/iio/magnetometer/mag3110.c b/drivers/iio/magnetometer/mag3110.c index 4d305a21c379..e96113ca39bd 100644 --- a/drivers/iio/magnetometer/mag3110.c +++ b/drivers/iio/magnetometer/mag3110.c @@ -56,6 +56,12 @@ struct mag3110_data { int sleep_val; struct regulator *vdd_reg; struct regulator *vddio_reg; + /* Ensure natural alignment of timestamp */ + struct { + __be16 channels[3]; + u8 temp; + s64 ts __aligned(8); + } scan; }; static int mag3110_request(struct mag3110_data *data) @@ -387,10 +393,9 @@ static irqreturn_t mag3110_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct mag3110_data *data = iio_priv(indio_dev); - u8 buffer[16]; /* 3 16-bit channels + 1 byte temp + padding + ts */ int ret; - ret = mag3110_read(data, (__be16 *) buffer); + ret = mag3110_read(data, data->scan.channels); if (ret < 0) goto done; @@ -399,10 +404,10 @@ static irqreturn_t mag3110_trigger_handler(int irq, void *p) MAG3110_DIE_TEMP); if (ret < 0) goto done; - buffer[6] = ret; + data->scan.temp = ret; } - iio_push_to_buffers_with_timestamp(indio_dev, buffer, + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev)); done: -- 2.27.0