From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753265AbdGLPGA (ORCPT ); Wed, 12 Jul 2017 11:06:00 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:47439 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753106AbdGLPF6 (ORCPT ); Wed, 12 Jul 2017 11:05:58 -0400 From: Guenter Roeck To: Henrik Rydberg Cc: Jean Delvare , linux-hwmon@vge.kernel.org, linux-kernel@vger.kernel.org, Guenter Roeck Subject: [PATCH] hwmon: (applesmc) Avoid buffer overruns Date: Wed, 12 Jul 2017 08:05:52 -0700 Message-Id: <1499871952-19192-1-git-send-email-linux@roeck-us.net> X-Mailer: git-send-email 2.7.4 X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: guenter@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org gcc 7.1 complains that the driver uses sprintf() and thus does not validate the length of output buffers. drivers/hwmon/applesmc.c: In function 'applesmc_show_fan_position': drivers/hwmon/applesmc.c:82:21: warning: '%d' directive writing between 1 and 5 bytes into a region of size 4 Fix the problem by using scnprintf() instead of sprintf() throughout the driver. Also explicitly limit the number of supported fans to avoid actual buffer overruns and thus invalid keys. Signed-off-by: Guenter Roeck --- drivers/hwmon/applesmc.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c index 0af7fd311979..76c34f4fde13 100644 --- a/drivers/hwmon/applesmc.c +++ b/drivers/hwmon/applesmc.c @@ -566,6 +566,8 @@ static int applesmc_init_smcreg_try(void) if (ret) return ret; s->fan_count = tmp[0]; + if (s->fan_count > 10) + s->fan_count = 10; ret = applesmc_get_lower_bound(&s->temp_begin, "T"); if (ret) @@ -811,7 +813,8 @@ static ssize_t applesmc_show_fan_speed(struct device *dev, char newkey[5]; u8 buffer[2]; - sprintf(newkey, fan_speed_fmt[to_option(attr)], to_index(attr)); + scnprintf(newkey, sizeof(newkey), fan_speed_fmt[to_option(attr)], + to_index(attr)); ret = applesmc_read_key(newkey, buffer, 2); speed = ((buffer[0] << 8 | buffer[1]) >> 2); @@ -834,7 +837,8 @@ static ssize_t applesmc_store_fan_speed(struct device *dev, if (kstrtoul(sysfsbuf, 10, &speed) < 0 || speed >= 0x4000) return -EINVAL; /* Bigger than a 14-bit value */ - sprintf(newkey, fan_speed_fmt[to_option(attr)], to_index(attr)); + scnprintf(newkey, sizeof(newkey), fan_speed_fmt[to_option(attr)], + to_index(attr)); buffer[0] = (speed >> 6) & 0xff; buffer[1] = (speed << 2) & 0xff; @@ -903,7 +907,7 @@ static ssize_t applesmc_show_fan_position(struct device *dev, char newkey[5]; u8 buffer[17]; - sprintf(newkey, FAN_ID_FMT, to_index(attr)); + scnprintf(newkey, sizeof(newkey), FAN_ID_FMT, to_index(attr)); ret = applesmc_read_key(newkey, buffer, 16); buffer[16] = 0; @@ -1116,7 +1120,8 @@ static int applesmc_create_nodes(struct applesmc_node_group *groups, int num) } for (i = 0; i < num; i++) { node = &grp->nodes[i]; - sprintf(node->name, grp->format, i + 1); + scnprintf(node->name, sizeof(node->name), grp->format, + i + 1); node->sda.index = (grp->option << 16) | (i & 0xffff); node->sda.dev_attr.show = grp->show; node->sda.dev_attr.store = grp->store; -- 2.7.4