From patchwork Sun Sep 20 11:27:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11787467 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 2C16E6CB for ; Sun, 20 Sep 2020 11:28:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1252D221EC for ; Sun, 20 Sep 2020 11:28:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600601307; bh=JKDqm3oz8WwgGan8wic+HdnAcdKtCjdQZz0V4syC/xc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dyBkjxFfAz6JiaNKAoWCR8D3hQfpe38HfK4RKyiJVnwag2cWRNO6OlEp5rQjOJOe5 AJYUVDe2qsG6lNRjfMfolDM2CIcQKq3TD/7NhLg0EGU8Z1sHVl7QZx1/cqOcm8selb j4Sf1KD3dhkseViK42i4f/ORGcIY8o6vv4lhMkiE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726279AbgITL20 (ORCPT ); Sun, 20 Sep 2020 07:28:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:39452 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726250AbgITL20 (ORCPT ); Sun, 20 Sep 2020 07:28:26 -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 D79EF21D43; Sun, 20 Sep 2020 11:28:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600601305; bh=JKDqm3oz8WwgGan8wic+HdnAcdKtCjdQZz0V4syC/xc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OQ5bfiwtxubCnCETYxNHS5Y6LPlS48QRSv7Kdaa+NrmwTXe9GYIqLyk0Qffhv+YmV qIIvfoHrWKR/7qBsh9PW9E1HXR+UsE+IdmGCWOVIHM2rohq0mqPLsW2+Lce8qFXyce XdKncqAKrrCInYGnk/bPRiDl7YjMIB+SVM0VR9vk= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Lars-Peter Clausen , Lorenzo Bianconi Subject: [PATCH v4 2/8] iio:light:st_uvis25: Fix timestamp alignment and prevent data leak. Date: Sun, 20 Sep 2020 12:27:36 +0100 Message-Id: <20200920112742.170751-3-jic23@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200920112742.170751-1-jic23@kernel.org> References: <20200920112742.170751-1-jic23@kernel.org> MIME-Version: 1.0 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() This data is allocated with kzalloc() so no data can leak apart from previous readings. A local unsigned int variable is used for the regmap call so it is clear there is no potential issue with writing into the padding of the structure. Fixes: 3025c8688c1e ("iio: light: add support for UVIS25 sensor") Reported-by: Lars-Peter Clausen Acked-by: Lorenzo Bianconi Signed-off-by: Jonathan Cameron --- v4: Drop the pointless masking. drivers/iio/light/st_uvis25.h | 5 +++++ drivers/iio/light/st_uvis25_core.c | 8 +++++--- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/iio/light/st_uvis25.h b/drivers/iio/light/st_uvis25.h index 78bc56aad129..283086887caf 100644 --- a/drivers/iio/light/st_uvis25.h +++ b/drivers/iio/light/st_uvis25.h @@ -27,6 +27,11 @@ struct st_uvis25_hw { struct iio_trigger *trig; bool enabled; int irq; + /* Ensure timestamp is naturally aligned */ + struct { + u8 chan; + s64 ts __aligned(8); + } scan; }; extern const struct dev_pm_ops st_uvis25_pm_ops; diff --git a/drivers/iio/light/st_uvis25_core.c b/drivers/iio/light/st_uvis25_core.c index a18a82e6bbf5..1055594b2276 100644 --- a/drivers/iio/light/st_uvis25_core.c +++ b/drivers/iio/light/st_uvis25_core.c @@ -232,17 +232,19 @@ static const struct iio_buffer_setup_ops st_uvis25_buffer_ops = { static irqreturn_t st_uvis25_buffer_handler_thread(int irq, void *p) { - u8 buffer[ALIGN(sizeof(u8), sizeof(s64)) + sizeof(s64)]; struct iio_poll_func *pf = p; struct iio_dev *iio_dev = pf->indio_dev; struct st_uvis25_hw *hw = iio_priv(iio_dev); + unsigned int val; int err; - err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, (int *)buffer); + err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, &val); if (err < 0) goto out; - iio_push_to_buffers_with_timestamp(iio_dev, buffer, + hw->scan.chan = val; + + iio_push_to_buffers_with_timestamp(iio_dev, &hw->scan, iio_get_time_ns(iio_dev)); out: