From patchwork Wed Jul 22 15:50:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11678733 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 8775214E3 for ; Wed, 22 Jul 2020 15:53:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D796208E4 for ; Wed, 22 Jul 2020 15:53:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433221; bh=Wlfui+VlY4bDZW0tV1inSNbem/cmMyKs1kjmlaZJbu4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=T2g42k+CzTMU8YvuXMrwM+Gg+b+vm1atvjKUFNopC5CZigOoe5Xb3bAkYDxbCQFRZ PtQ1F0CU4wFr/9dV+MPI7Bl4JvDN4EeijFt0Txi4SSuevFWOIUHUZju93sHTXD6u1j KFtz84mZxZtS6Q1YfCMR0t5TC5SC+J0ewPbcAeOM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730581AbgGVPxl (ORCPT ); Wed, 22 Jul 2020 11:53:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:35846 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxk (ORCPT ); Wed, 22 Jul 2020 11:53:40 -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 204B42084D; Wed, 22 Jul 2020 15:53:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433220; bh=Wlfui+VlY4bDZW0tV1inSNbem/cmMyKs1kjmlaZJbu4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hq0TM+F6Nfz5kUB41o3SvMR94PglPhTEmg5+fEXWnIikrjxi8uKZewypwDd00PVnK NJ4lG/lBTFaAajHIXMuSfiDpcA8hk5i+8rNwW+bLbvGWPKBwWIP2jQRTurLRujsgx8 QVxmmqYMqfI1TaY+om7/Gg9BEiOrP8oNrYZvIuwM= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , =?utf-8?q?M=C3=A5rten_Linda?= =?utf-8?q?hl?= Subject: [PATCH v3 21/27] iio:adc:ti-adc084s021 Fix alignment and data leak issues. Date: Wed, 22 Jul 2020 16:50:57 +0100 Message-Id: <20200722155103.979802-22-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 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. The force alignment of ts is not strictly necessary in this case but reduces the fragility of the code. Fixes: 3691e5a69449 ("iio: adc: add driver for the ti-adc084s021 chip") Reported-by: Lars-Peter Clausen Cc: Mårten Lindahl Signed-off-by: Jonathan Cameron --- drivers/iio/adc/ti-adc084s021.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/iio/adc/ti-adc084s021.c b/drivers/iio/adc/ti-adc084s021.c index 9017e1e24273..dfba34834a57 100644 --- a/drivers/iio/adc/ti-adc084s021.c +++ b/drivers/iio/adc/ti-adc084s021.c @@ -26,6 +26,11 @@ struct adc084s021 { struct spi_transfer spi_trans; struct regulator *reg; struct mutex lock; + /* Buffer used to align data */ + struct { + __be16 channels[4]; + s64 ts __aligned(8); + } scan; /* * DMA (thus cache coherency maintenance) requires the * transfer buffers to live in their own cache line. @@ -141,14 +146,13 @@ static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc) struct iio_poll_func *pf = pollfunc; struct iio_dev *indio_dev = pf->indio_dev; struct adc084s021 *adc = iio_priv(indio_dev); - __be16 data[8] = {0}; /* 4 * 16-bit words of data + 8 bytes timestamp */ mutex_lock(&adc->lock); - if (adc084s021_adc_conversion(adc, &data) < 0) + if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0) dev_err(&adc->spi->dev, "Failed to read data\n"); - 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)); mutex_unlock(&adc->lock); iio_trigger_notify_done(indio_dev->trig);