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 6DC88C433E4 for ; Wed, 22 Jul 2020 15:53:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4B44B207DD for ; Wed, 22 Jul 2020 15:53:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433192; bh=Zmnk4xZ1pGh8I1k4TrpFM63YFE/SARDLHj6dZZhfs7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=z5IOV0sicy/YxcfBVTcgStmbka2rYnwVpLRomAHh8EtvmI6d5hf7IMl0vUi8vt6BV 65H/iXoNlMb+kGejaA1m3bMBEd0mG/7ANAHUIhIf0wu85SNlG6pF3VHVjvR0+J3e6A 7MNbvkycq9TuCJo5yScdmOX7eaVkg+MWtd28svkA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727891AbgGVPxM (ORCPT ); Wed, 22 Jul 2020 11:53:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:35526 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxL (ORCPT ); Wed, 22 Jul 2020 11:53:11 -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 63368207CD; Wed, 22 Jul 2020 15:53:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433191; bh=Zmnk4xZ1pGh8I1k4TrpFM63YFE/SARDLHj6dZZhfs7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kM2IC8p45ZZPnBIF2msHFKqXlBSdv32Hmrbq2l8ikpfGnUAgUdqVcBXHomyYL/ALD NyHN9bqdlQmeYasYeDXZvfjElEr9J4UQkcmDbfp6oHL0+WAfL3ITQVncN+8WczjvzM QFIo1tG/QO800k6gGDoiiREOqKCcry4Dy3ACNT40= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron Subject: [PATCH v3 02/27] iio:accel:mma8452: Fix timestamp alignment and prevent data leak. Date: Wed, 22 Jul 2020 16:50:38 +0100 Message-Id: <20200722155103.979802-3-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 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 ba27f8673131..1cf2b5db26ca 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: -- 2.27.0