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=-11.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 06788C43468 for ; Mon, 21 Sep 2020 16:32:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3EE0235F9 for ; Mon, 21 Sep 2020 16:31:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600705919; bh=LsR533p9yB5t7YUneI1L6ClLmqw23x4NqPSlHi85swQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MnRGOTayo5URPMBudPaL+czDHbkdR3vknd0YeWr85tMuewscFT9iRNj4ShKdhYiK5 EBm74j74ORjSuBZB1C8uix4evGXGoHlWN2mdtHwsyp+YnzCCnV7ylotGLvu4ww2cA7 6eVVadRw8xYCCAQfun8leBMx8OIJMax7czdSdIBI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728344AbgIUQb7 (ORCPT ); Mon, 21 Sep 2020 12:31:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:57044 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728246AbgIUQbz (ORCPT ); Mon, 21 Sep 2020 12:31:55 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9FE0C2396F; Mon, 21 Sep 2020 16:31:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600705915; bh=LsR533p9yB5t7YUneI1L6ClLmqw23x4NqPSlHi85swQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Obv0JawuU+X62l0E7R6BI0sno3cXF17CYExy0Le3vcmf8BsJ9GI55YUV50UZbMzYx zNHS+UPWz+2VrIRUPDUQ5CVzYAAQCUtSfZh1Ni1BeX3o6zwbvoGx8CUUJzu303XVQF 9qBzroLZ1KfvTxSVGnmqER+SUEsR1ltLM6ZtVxps= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Andy Shevchenko , Stable@vger.kernel.org Subject: [PATCH 4.4 14/46] iio:accel:mma8452: Fix timestamp alignment and prevent data leak. Date: Mon, 21 Sep 2020 18:27:30 +0200 Message-Id: <20200921162034.006731941@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200921162033.346434578@linuxfoundation.org> References: <20200921162033.346434578@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jonathan Cameron commit 89226a296d816727405d3fea684ef69e7d388bd8 upstream. 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 Reviewed-by: Andy Shevchenko Cc: Signed-off-by: Greg Kroah-Hartman --- drivers/iio/accel/mma8452.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/drivers/iio/accel/mma8452.c +++ b/drivers/iio/accel/mma8452.c @@ -96,6 +96,12 @@ struct mma8452_data { u8 ctrl_reg1; u8 data_cfg; const struct mma_chip_info *chip_info; + + /* Ensure correct alignment of time stamp when present */ + struct { + __be16 channels[3]; + s64 ts __aligned(8); + } buffer; }; /** @@ -700,14 +706,13 @@ static irqreturn_t mma8452_trigger_handl 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()); done: