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.as...@objecthunter.net>
---
tools/thermal/tmon/sysfs.c | 12 +++++++-----
tools/thermal/tmon/tmon.c | 1 -
2 files changed, 7 insertions(+), 6 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;
diff --git a/tools/thermal/tmon/tmon.c b/tools/thermal/tmon/tmon.c
index 9aa19652e8e8..b43138f8b862 100644
--- 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);
--
2.16.2
