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 EB027C433FE for ; Wed, 22 Jul 2020 15:53:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBFCF207E8 for ; Wed, 22 Jul 2020 15:53:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433219; bh=w3LGe39IerBHvYTv/VvKMnI3lLTCyXa1a7u1VSCcP78=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gms4Y9QP7a6y6ts5qB5sd7KJiJvenCahGy2G7uadW/PcCeyvgRmGXFuUcVdGxvCxa V4aaw2RU80jHGpLRaCbNMqe0yzphYRpp25Is3aUUdr/6WwiI5FJGy3CZmHqGbceE6l RKMdwxwn/Eg3/3sI6nDEBqFjhn8LfwIfbIJfk4Oc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730468AbgGVPxj (ORCPT ); Wed, 22 Jul 2020 11:53:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:35822 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxj (ORCPT ); Wed, 22 Jul 2020 11:53:39 -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 ACF82207CD; Wed, 22 Jul 2020 15:53:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433218; bh=w3LGe39IerBHvYTv/VvKMnI3lLTCyXa1a7u1VSCcP78=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lvTYj74jL5dcOiob8DEV5TcnWMhGdX0izdY0UUASib/Z7PuDJhygJI3tVl8DzsnJ0 BL+VwxlxBRhJB6mw3dya/0LAARmMUnXWrpthtLmr6XJxXVCl+PJdGp4waNJq62d68Q DUY989B5t6URjx2y/3Ko9uh1TXOcVSXuFGenDCnc= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron Subject: [PATCH v3 20/27] iio:adc:ti-adc081c Fix alignment and data leak issues Date: Wed, 22 Jul 2020 16:50:56 +0100 Message-Id: <20200722155103.979802-21-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(). This data is allocated with kzalloc so no data can leak apart from previous readings. The eplicit alignment of ts is necessary to ensure correct padding on x86_32 where s64 is only aligned to 4 bytes. Fixes: 08e05d1fce5c (" ti-adc081c: Initial triggered buffer support") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron --- drivers/iio/adc/ti-adc081c.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/iio/adc/ti-adc081c.c b/drivers/iio/adc/ti-adc081c.c index 9426f70a8005..cf63983a54d9 100644 --- a/drivers/iio/adc/ti-adc081c.c +++ b/drivers/iio/adc/ti-adc081c.c @@ -33,6 +33,12 @@ struct adc081c { /* 8, 10 or 12 */ int bits; + + /* Ensure natural alignment of buffer elements */ + struct { + u16 channel; + s64 ts __aligned(8); + } scan; }; #define REG_CONV_RES 0x00 @@ -128,14 +134,13 @@ static irqreturn_t adc081c_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct adc081c *data = iio_priv(indio_dev); - u16 buf[8]; /* 2 bytes data + 6 bytes padding + 8 bytes timestamp */ int ret; ret = i2c_smbus_read_word_swapped(data->i2c, REG_CONV_RES); if (ret < 0) goto out; - buf[0] = ret; - iio_push_to_buffers_with_timestamp(indio_dev, buf, + data->scan.channel = ret; + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev)); out: iio_trigger_notify_done(indio_dev->trig); -- 2.27.0