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 165B4C43459 for ; Wed, 22 Jul 2020 15:53:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8C1420771 for ; Wed, 22 Jul 2020 15:53:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433230; bh=RNNl6bAHVwJ30y4Xg0mqag0ifFcEY3vNyFLgoVTF9e8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dVb+gOWI9YZbXSSDHj2+JfPvusy8zrXupQ9uicmpQlQIrp+OezCm1mhSpEzbrmRb2 jA7CAT9kj0dc0ze4GsoIB92GmpHJIP8EvnDqS87x3V/p7lAqbnIPkO32uaqUsK+fWH wD8RK6hEYstVOwUVf4vudW9zY1n2exgD4PU1gDuY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730116AbgGVPxu (ORCPT ); Wed, 22 Jul 2020 11:53:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:35946 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxu (ORCPT ); Wed, 22 Jul 2020 11:53:50 -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 8EA5E207CD; Wed, 22 Jul 2020 15:53:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433229; bh=RNNl6bAHVwJ30y4Xg0mqag0ifFcEY3vNyFLgoVTF9e8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ybLJKj3SbMSTMD396ZTBozMWNBgmZOrsWCQJZ+NzwbfZXcdcesd9sFGvDA+G28HZX OSxq43Zqn43+oFCW7dpH/5w+IjXTFTU7URJXO0qlcPmpoM1fspmTr7lwK8OOjgE0bg AmTZAMjXPwN1eYz1uycrQJ7dGsgaZpOOrYSg4VNA= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Akinobu Mita Subject: [PATCH v3 27/27] iio:adc:max1118 Fix alignment of timestamp and data leak issues Date: Wed, 22 Jul 2020 16:51:03 +0100 Message-Id: <20200722155103.979802-28-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 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() data. This data is allocated with kzalloc so no data can leak apart from previous readings. The explicit alignment of ts is necessary to ensure correct padding on architectures where s64 is only 4 bytes aligned such as x86_32. Fixes: a9e9c7153e96 ("iio: adc: add max1117/max1118/max1119 ADC driver") Reported-by: Lars-Peter Clausen Cc: Akinobu Mita Signed-off-by: Jonathan Cameron --- drivers/iio/adc/max1118.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/iio/adc/max1118.c b/drivers/iio/adc/max1118.c index 01b20e420ac4..6efb0b43d938 100644 --- a/drivers/iio/adc/max1118.c +++ b/drivers/iio/adc/max1118.c @@ -36,6 +36,11 @@ struct max1118 { struct spi_device *spi; struct mutex lock; struct regulator *reg; + /* Ensure natural alignment of buffer elements */ + struct { + u8 channels[2]; + s64 ts __aligned(8); + } scan; u8 data ____cacheline_aligned; }; @@ -166,7 +171,6 @@ static irqreturn_t max1118_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct max1118 *adc = iio_priv(indio_dev); - u8 data[16] = { }; /* 2x 8-bit ADC data + padding + 8 bytes timestamp */ int scan_index; int i = 0; @@ -184,10 +188,10 @@ static irqreturn_t max1118_trigger_handler(int irq, void *p) goto out; } - data[i] = ret; + adc->scan.channels[i] = ret; i++; } - iio_push_to_buffers_with_timestamp(indio_dev, data, + iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan, iio_get_time_ns(indio_dev)); out: mutex_unlock(&adc->lock); -- 2.27.0