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authorFrank Asseg <frank.asseg@objecthunter.net>2018-03-12 21:57:06 +0300
committerJiri Kosina <jkosina@suse.cz>2018-03-27 10:51:23 +0300
commit6c59f64b7ecf2bccbe73931d7d573d66ed13b537 (patch)
tree3e0be7a9e2ccb0a8372ab0c3d9c7a1faf882d9a4 /tools/thermal/tmon/sysfs.c
parentb903036aad6c46f0c94b3a58c86f7467776a5dcf (diff)
downloadlinux-6c59f64b7ecf2bccbe73931d7d573d66ed13b537.tar.xz
tools/thermal: tmon: fix for segfault
Fixes a segfault occurring when e.g. <TAB> 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 <frank.asseg@objecthunter.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'tools/thermal/tmon/sysfs.c')
-rw-r--r--tools/thermal/tmon/sysfs.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/tools/thermal/tmon/sysfs.c b/tools/thermal/tmon/sysfs.c
index 1c12536f2081..18f523557983 100644
--- 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;