From patchwork Sun Sep 20 11:27:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11787473 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 827BB6CB for ; Sun, 20 Sep 2020 11:28:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6ABFC21BE5 for ; Sun, 20 Sep 2020 11:28:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600601312; bh=qKkiifeQgZBculEoovyDxk+Ss7PduJetxuA0LhIeAI8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lynMo6JR5e/LUWfnKG7+938qrWtIHffSkhds+PpoLVcl3XGcya4Hb2V6OdukXrao/ h+rNAkxeg5N9tgnlPG03bBhPcjAdZxaBaszEWG4HyMznCh2qHbrVWkQ3IxxNTTqLmr szhOk4wkfEoYntmd3aT/4GmZJdiRqWsDZ+gHs5Xw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726250AbgITL2b (ORCPT ); Sun, 20 Sep 2020 07:28:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:39486 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726285AbgITL2b (ORCPT ); Sun, 20 Sep 2020 07:28:31 -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 1AD5B23119; Sun, 20 Sep 2020 11:28:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600601310; bh=qKkiifeQgZBculEoovyDxk+Ss7PduJetxuA0LhIeAI8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MuzWAxBvhRuTC9rYMPpMEd0amHWQ8AoNpplyG4V8y/OSnPF8sQD4Rp3NkGGysqLa0 SCVGB0YN+0AAvzSX/tVxvos91VmBtPO1e7A/B0Zr6IvQOxXTPotOp49w9izIvi0X8y 7F5T6rXfVS+RF7QT1qJ5nYJlV5poTJagHXkKzgt0= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Lars-Peter Clausen , Daniel Baluta , Daniel Baluta Subject: [PATCH v4 5/8] iio:imu:bmi160: Fix alignment and data leak issues Date: Sun, 20 Sep 2020 12:27:39 +0100 Message-Id: <20200920112742.170751-6-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 array in the iio_priv() data with alignment explicitly requested. This data is allocated with kzalloc() so no data can leak apart from previous readings. In this driver, depending on which channels are enabled, the timestamp can be in a number of locations. Hence we cannot use a structure to specify the data layout without it being misleading. Fixes: 77c4ad2d6a9b ("iio: imu: Add initial support for Bosch BMI160") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron Cc: Daniel Baluta Cc: Daniel Baluta --- v4: Improve comments and carry forwards shorter length. drivers/iio/imu/bmi160/bmi160.h | 7 +++++++ drivers/iio/imu/bmi160/bmi160_core.c | 6 ++---- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/iio/imu/bmi160/bmi160.h b/drivers/iio/imu/bmi160/bmi160.h index a82e040bd109..32c2ea2d7112 100644 --- a/drivers/iio/imu/bmi160/bmi160.h +++ b/drivers/iio/imu/bmi160/bmi160.h @@ -10,6 +10,13 @@ struct bmi160_data { struct iio_trigger *trig; struct regulator_bulk_data supplies[2]; struct iio_mount_matrix orientation; + /* + * Ensure natural alignment for timestamp if present. + * Max length needed: 2 * 3 channels + 4 bytes padding + 8 byte ts. + * If fewer channels are enabled, less space may be needed, as + * long as the timestamp is still aligned to 8 bytes. + */ + __le16 buf[12] __aligned(8); }; extern const struct regmap_config bmi160_regmap_config; diff --git a/drivers/iio/imu/bmi160/bmi160_core.c b/drivers/iio/imu/bmi160/bmi160_core.c index 39fea58dd308..82f03a4dc47a 100644 --- a/drivers/iio/imu/bmi160/bmi160_core.c +++ b/drivers/iio/imu/bmi160/bmi160_core.c @@ -427,8 +427,6 @@ static irqreturn_t bmi160_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct bmi160_data *data = iio_priv(indio_dev); - __le16 buf[12]; - /* 2 sens x 3 axis x __le16 + 2 x __le16 pad + 4 x __le16 tstamp */ int i, ret, j = 0, base = BMI160_REG_DATA_MAGN_XOUT_L; __le16 sample; @@ -438,10 +436,10 @@ static irqreturn_t bmi160_trigger_handler(int irq, void *p) &sample, sizeof(sample)); if (ret) goto done; - buf[j++] = sample; + data->buf[j++] = sample; } - iio_push_to_buffers_with_timestamp(indio_dev, buf, pf->timestamp); + iio_push_to_buffers_with_timestamp(indio_dev, data->buf, pf->timestamp); done: iio_trigger_notify_done(indio_dev->trig); return IRQ_HANDLED;