From patchwork Sun Jun 7 15:53:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11591677 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 24B58912 for ; Sun, 7 Jun 2020 15:56:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D94A207C3 for ; Sun, 7 Jun 2020 15:56:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545388; bh=kjVkMyHoJBjLj1sXC/JYIQ00cKMGLqMTsjg0E4teTiM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=h2dmmOPBLwKMiAMOJwv5p14n6kutK1mCqSsVmgNRE6WDuoYK1TCIpuFBIRsHnQHjo hGMTzOO0LPg4DL7UXNCde+zn5LZYmf6VNO3sYXR3TtLpjyedF+NveujwuYmQnPIFtV 2Q4K613B8bTM6DEb5yogdW0mILfxxS42Vm6E8HkI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726694AbgFGP41 (ORCPT ); Sun, 7 Jun 2020 11:56:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:57320 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726631AbgFGP41 (ORCPT ); Sun, 7 Jun 2020 11:56:27 -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 E741C2077D; Sun, 7 Jun 2020 15:56:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545386; bh=kjVkMyHoJBjLj1sXC/JYIQ00cKMGLqMTsjg0E4teTiM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ThSQzA1SwaFGnaq1fj5FxgzH1aGjQrYXdTkTCNTKGU4kPC38FHp/Z2reTzt6iD1Hg gDvTWnwfUtbOLgo/adqb4K7KSSryL9YYO4KDOY2s24/w2ToMGvgCtX0BK/M2AYunVh MAqvWmn5GwHWrR3nMrjmzvwPS5alHTBwxoJoMAVE= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Lars-Peter Clausen Subject: [PATCH 09/32] iio:light:max44000 Fix timestamp alignment and prevent data leak. Date: Sun, 7 Jun 2020 16:53:45 +0100 Message-Id: <20200607155408.958437-10-jic23@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200607155408.958437-1-jic23@kernel.org> References: <20200607155408.958437-1-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 a 16 byte 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 appart from previous readings. It is necessary to force the alignment of ts to avoid the padding on x86_32 being different from 64 bit platorms (it alows for 4 bytes aligned 8 byte types. Fixes: 06ad7ea10e2b ("max44000: Initial triggered buffer support") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron --- drivers/iio/light/max44000.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/iio/light/max44000.c b/drivers/iio/light/max44000.c index aa8ed1e3e89a..b8e721bced5b 100644 --- a/drivers/iio/light/max44000.c +++ b/drivers/iio/light/max44000.c @@ -75,6 +75,11 @@ struct max44000_data { struct mutex lock; struct regmap *regmap; + /* Ensure naturally aligned timestamp */ + struct { + u16 channels[2]; + s64 ts __aligned(8); + } scan; }; /* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */ @@ -488,7 +493,6 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct max44000_data *data = iio_priv(indio_dev); - u16 buf[8]; /* 2x u16 + padding + 8 bytes timestamp */ int index = 0; unsigned int regval; int ret; @@ -498,17 +502,17 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p) ret = max44000_read_alsval(data); if (ret < 0) goto out_unlock; - buf[index++] = ret; + data->scan.channels[index++] = ret; } if (test_bit(MAX44000_SCAN_INDEX_PRX, indio_dev->active_scan_mask)) { ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, ®val); if (ret < 0) goto out_unlock; - buf[index] = regval; + data->scan.channels[index] = regval; } mutex_unlock(&data->lock); - iio_push_to_buffers_with_timestamp(indio_dev, buf, + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev)); iio_trigger_notify_done(indio_dev->trig); return IRQ_HANDLED;