From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1424801AbeE1LqR (ORCPT ); Mon, 28 May 2018 07:46:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:58940 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423260AbeE1LK4 (ORCPT ); Mon, 28 May 2018 07:10:56 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Frank Asseg , Jiri Kosina , Sasha Levin Subject: [PATCH 4.16 117/272] tools/thermal: tmon: fix for segfault Date: Mon, 28 May 2018 12:02:30 +0200 Message-Id: <20180528100250.979378409@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180528100240.256525891@linuxfoundation.org> References: <20180528100240.256525891@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Frank Asseg [ Upstream commit 6c59f64b7ecf2bccbe73931d7d573d66ed13b537 ] Fixes a segfault occurring when e.g. is pressed multiple times in the ncurses tmon application. The segfault is caused by incrementing cur_thermal_record in the main function without checking if it's value reached NR_THERMAL_RECORD immediately. Since the boundary check only occurred in update_thermal_data a race condition existed, which lead to an attempted read beyond the last element of the trec array. The fix was implemented by moving the cur_thermal_record incrementation to the update_thermal_data function using a temporary variable on which the boundary condition is checked before updating cur_thread_record, so that the variable is never incremented beyond the trec array's boundary. It seems the segfault does not occur on every machine: On a HP EliteBook G4 the segfault happens, while it does not happen on a Thinkpad T540p. Signed-off-by: Frank Asseg Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- tools/thermal/tmon/sysfs.c | 12 +++++++----- tools/thermal/tmon/tmon.c | 1 - 2 files changed, 7 insertions(+), 6 deletions(-) --- a/tools/thermal/tmon/sysfs.c +++ b/tools/thermal/tmon/sysfs.c @@ -486,6 +486,7 @@ int zone_instance_to_index(int zone_inst int update_thermal_data() { int i; + int next_thermal_record = cur_thermal_record + 1; char tz_name[256]; static unsigned long samples; @@ -495,9 +496,9 @@ int update_thermal_data() } /* circular buffer for keeping historic data */ - if (cur_thermal_record >= NR_THERMAL_RECORDS) - cur_thermal_record = 0; - gettimeofday(&trec[cur_thermal_record].tv, NULL); + if (next_thermal_record >= NR_THERMAL_RECORDS) + next_thermal_record = 0; + gettimeofday(&trec[next_thermal_record].tv, NULL); if (tmon_log) { fprintf(tmon_log, "%lu ", ++samples); fprintf(tmon_log, "%3.1f ", p_param.t_target); @@ -507,11 +508,12 @@ int update_thermal_data() snprintf(tz_name, 256, "%s/%s%d", THERMAL_SYSFS, TZONE, ptdata.tzi[i].instance); sysfs_get_ulong(tz_name, "temp", - &trec[cur_thermal_record].temp[i]); + &trec[next_thermal_record].temp[i]); if (tmon_log) fprintf(tmon_log, "%lu ", - trec[cur_thermal_record].temp[i]/1000); + trec[next_thermal_record].temp[i] / 1000); } + cur_thermal_record = next_thermal_record; for (i = 0; i < ptdata.nr_cooling_dev; i++) { char cdev_name[256]; unsigned long val; --- a/tools/thermal/tmon/tmon.c +++ b/tools/thermal/tmon/tmon.c @@ -336,7 +336,6 @@ int main(int argc, char **argv) show_data_w(); show_cooling_device(); } - cur_thermal_record++; time_elapsed += ticktime; controller_handler(trec[0].temp[target_tz_index] / 1000, &yk);