From patchwork Mon May 25 17:06:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11569115 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 12EF0739 for ; Mon, 25 May 2020 17:09:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F017D20776 for ; Mon, 25 May 2020 17:09:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590426566; bh=j5orTSX/27oQbVPk5oYRFnnZSh0KwF86SEvaraRl1TE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=IygVibJFH+OMBwhzCxEwAz8hgRXKvB/k85x/mdCn3qWYSAqRw6q4nBxLui4t9/NdW lBJ5r9Azi5HNgpFaTv2wQ8pCxYdhWVR+P7cHR4dLpHdvh+VnQHo6tq5nMfoH2EAkvZ D/KGYKM2EA/0KeLbztzqT6O1GfD8oHTTJ4KYMMhg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391305AbgEYRJZ (ORCPT ); Mon, 25 May 2020 13:09:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:42866 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391301AbgEYRJZ (ORCPT ); Mon, 25 May 2020 13:09:25 -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 B4B4120878; Mon, 25 May 2020 17:09:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590426564; bh=j5orTSX/27oQbVPk5oYRFnnZSh0KwF86SEvaraRl1TE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1eWOV8hNQt1cVwkAn6S8nbpMZt4SnfhDYL01vLC3hhAfumXQIuNmBwdjFR+khLGyW WAUwbB6cJfhmf3vL3d9HbeFU/AnfhnsTpMumpwn7rvUxkPEtazzv40AYDUKlq1uXCn UK8vZnv6+HsKr3KwBkvsohEOupZdWK4rE5LBnmo4= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Jonathan Cameron , Lars-Peter Clausen , Dan Murphy Subject: [PATCH 20/25] iio:adc:ti-ads124s08 Fix alignment and data leak issues. Date: Mon, 25 May 2020 18:06:23 +0100 Message-Id: <20200525170628.503283-21-jic23@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200525170628.503283-1-jic23@kernel.org> References: <20200525170628.503283-1-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() data with alignment explicitly requested. This data is allocated with kzalloc so no data can leak apart from previous readings. Fixes: e717f8c6dfec ("iio: adc: Add the TI ads124s08 ADC code") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron Cc: Dan Murphy --- drivers/iio/adc/ti-ads124s08.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/iio/adc/ti-ads124s08.c b/drivers/iio/adc/ti-ads124s08.c index f1ee3b1e2827..fb0da62b09f5 100644 --- a/drivers/iio/adc/ti-ads124s08.c +++ b/drivers/iio/adc/ti-ads124s08.c @@ -99,6 +99,11 @@ struct ads124s_private { struct gpio_desc *reset_gpio; struct spi_device *spi; struct mutex lock; + /* + * Used to correctly align data. + * Ensure timestamp is naturally aligned. + */ + u32 buffer[ADS124S08_MAX_CHANNELS + sizeof(s64)/sizeof(u16)] __aligned(8); u8 data[5] ____cacheline_aligned; }; @@ -269,7 +274,6 @@ static irqreturn_t ads124s_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct ads124s_private *priv = iio_priv(indio_dev); - u32 buffer[ADS124S08_MAX_CHANNELS + sizeof(s64)/sizeof(u16)]; int scan_index, j = 0; int ret; @@ -284,7 +288,7 @@ static irqreturn_t ads124s_trigger_handler(int irq, void *p) if (ret) dev_err(&priv->spi->dev, "Start ADC conversions failed\n"); - buffer[j] = ads124s_read(indio_dev, scan_index); + priv->buffer[j] = ads124s_read(indio_dev, scan_index); ret = ads124s_write_cmd(indio_dev, ADS124S08_STOP_CONV); if (ret) dev_err(&priv->spi->dev, "Stop ADC conversions failed\n"); @@ -292,7 +296,7 @@ static irqreturn_t ads124s_trigger_handler(int irq, void *p) j++; } - iio_push_to_buffers_with_timestamp(indio_dev, buffer, + iio_push_to_buffers_with_timestamp(indio_dev, priv->buffer, pf->timestamp); iio_trigger_notify_done(indio_dev->trig);