From patchwork Wed Jul 22 15:50:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11678697 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 29CB613A4 for ; Wed, 22 Jul 2020 15:53:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 113D0207E8 for ; Wed, 22 Jul 2020 15:53:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433194; bh=kgN38xlg5rt6u1iO3jr5SziroURYQCtFvw17Kfczz1w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qnUXl7hsMlQB28+XE3X3jt69W135LPaemWMGB0rmqojmohwDjwCQ/w2LtJV3TnGPP V6sYw2igfiTCVulQ6VDbjKSgzYENhmeiApvo1tqvkj3NegjS9Q4MxCZYuSq+rTvTr/ 96dMobGBM8Iatnrgjy6tqmNkHv5dQsf/qvXL0MTs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727933AbgGVPxN (ORCPT ); Wed, 22 Jul 2020 11:53:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:35538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxN (ORCPT ); Wed, 22 Jul 2020 11:53:13 -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 CCA3320771; Wed, 22 Jul 2020 15:53:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433193; bh=kgN38xlg5rt6u1iO3jr5SziroURYQCtFvw17Kfczz1w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=izPF1xw4VRlUhMEJ5ONliN0OyLUC+8HT/0UFoyUMTTMPhUVHoaZdKqsKutmPSqii6 x8RfLcz0+7SnVWdrtS7ldlv4mDqLRFGbPxbNbOLAdSYIX500NzslJVIdU1V2tvFuQq 9bdIq6o7XyNWtlrVx6q9d3lxSE3V/MqesZP6ln7E= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Srinivas Pandruvada Subject: [PATCH v3 03/27] iio:accel:bmc150-accel: Fix timestamp alignment and prevent data leak. Date: Wed, 22 Jul 2020 16:50:39 +0100 Message-Id: <20200722155103.979802-4-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 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 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 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. Fixes tag is beyond some major refactoring so likely manual backporting would be needed to get that far back. Whilst the force alignment of the ts is not strictly necessary, it does make the code less fragile. Fixes: 3bbec9773389 ("iio: bmc150_accel: add support for hardware fifo") Reported-by: Lars-Peter Clausen Cc: Srinivas Pandruvada Signed-off-by: Jonathan Cameron Acked-by: Srinivas Pandruvada --- drivers/iio/accel/bmc150-accel-core.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c index 24864d9dfab5..48435865fdaf 100644 --- a/drivers/iio/accel/bmc150-accel-core.c +++ b/drivers/iio/accel/bmc150-accel-core.c @@ -189,6 +189,14 @@ struct bmc150_accel_data { struct mutex mutex; u8 fifo_mode, watermark; s16 buffer[8]; + /* + * Ensure there is sufficient space and correct alignment for + * the timestamp if enabled + */ + struct { + __le16 channels[3]; + s64 ts __aligned(8); + } scan; u8 bw_bits; u32 slope_dur; u32 slope_thres; @@ -922,15 +930,16 @@ static int __bmc150_accel_fifo_flush(struct iio_dev *indio_dev, * now. */ for (i = 0; i < count; i++) { - u16 sample[8]; int j, bit; j = 0; for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) - memcpy(&sample[j++], &buffer[i * 3 + bit], 2); + memcpy(&data->scan.channels[j++], &buffer[i * 3 + bit], + sizeof(data->scan.channels[0])); - iio_push_to_buffers_with_timestamp(indio_dev, sample, tstamp); + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, + tstamp); tstamp += sample_period; }