From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gateway22.websitewelcome.com ([192.185.47.168]:46217 "EHLO gateway22.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729128AbeHOQ1u (ORCPT ); Wed, 15 Aug 2018 12:27:50 -0400 Received: from cm15.websitewelcome.com (cm15.websitewelcome.com [100.42.49.9]) by gateway22.websitewelcome.com (Postfix) with ESMTP id A4EA645867 for ; Wed, 15 Aug 2018 08:15:12 -0500 (CDT) Date: Wed, 15 Aug 2018 08:14:37 -0500 From: "Gustavo A. R. Silva" To: Guenter Roeck , Jean Delvare Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] hwmon: (nct6775) Fix potential Spectre v1 Message-ID: <20180815131437.GA25639@embeddedor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-hwmon-owner@vger.kernel.org List-Id: linux-hwmon@vger.kernel.org val can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: vers/hwmon/nct6775.c:2698 store_pwm_weight_temp_sel() warn: potential spectre issue 'data->temp_src' [r] Fix this by sanitizing val before using it to index data->temp_src Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva --- drivers/hwmon/nct6775.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c index c6bd61e..944f5b6 100644 --- a/drivers/hwmon/nct6775.c +++ b/drivers/hwmon/nct6775.c @@ -63,6 +63,7 @@ #include #include #include +#include #include "lm75.h" #define USE_ALTERNATE @@ -2689,6 +2690,7 @@ store_pwm_weight_temp_sel(struct device *dev, struct device_attribute *attr, return err; if (val > NUM_TEMP) return -EINVAL; + val = array_index_nospec(val, NUM_TEMP + 1); if (val && (!(data->have_temp & BIT(val - 1)) || !data->temp_src[val - 1])) return -EINVAL; -- 2.7.4