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 03748C43445 for ; Wed, 22 Jul 2020 15:53:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF6D6208E4 for ; Wed, 22 Jul 2020 15:53:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433224; bh=BIatcbE+CfKNYNAPsaxb4Ys2/kUbi6raTVuQg4Z0Ct0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TIvb+DhyE+//jq8JlBMwFDthVN5XiUdhVqlqmPBUGYUb9KVBz3CDl9Cqz1jsvECgQ wlULBEn42vTTVD9jiDhihHvLgMs+nj+ywVNCCblABltBPueQaW12UBJk9rafbyrSoH 5bnd2egfZ3IjbT6UaPF1yLI16IK07ciIvKvpwrD4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730591AbgGVPxo (ORCPT ); Wed, 22 Jul 2020 11:53:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:35872 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxo (ORCPT ); Wed, 22 Jul 2020 11:53:44 -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 1C4562080D; 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=1595433223; bh=BIatcbE+CfKNYNAPsaxb4Ys2/kUbi6raTVuQg4Z0Ct0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GQsZ1n0WU3Ta4+FUBTZlfeY+NFRMf6wyNYFvgaL23fAKaHOdxrX6xDaQ5G5ayNRnO SKRZUYgtMwsMKEvfoCtORjg8seS4etiH4eTh+/gasi7/rAhe7F3E9Fumz4ZdC9yyYI e7RLa52gzgeVkPSO3NlcgTWIKMqlZSzHihVZcg+M= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Dan Murphy Subject: [PATCH v3 23/27] iio:adc:ti-ads124s08 Fix alignment and data leak issues. Date: Wed, 22 Jul 2020 16:50:59 +0100 Message-Id: <20200722155103.979802-24-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 with alignment explicitly requested. This data is allocated with kzalloc so no data can leak apart from previous readings. In this driver the timestamp can end up in various different locations depending on what other channels are enabled. As a result, we don't use a structure to specify it's position as that would be missleading. Fixes: e717f8c6dfec ("iio: adc: Add the TI ads124s08 ADC code") Reported-by: Lars-Peter Clausen Cc: Dan Murphy Signed-off-by: Jonathan Cameron --- 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 4b4fbe33930c..734ee5d82ff6 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); -- 2.27.0