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| author | Frank Asseg <frank.asseg@objecthunter.net> | 2018-03-12 21:57:06 +0300 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2018-03-27 10:51:23 +0300 |
| commit | 6c59f64b7ecf2bccbe73931d7d573d66ed13b537 (patch) | |
| tree | 3e0be7a9e2ccb0a8372ab0c3d9c7a1faf882d9a4 /tools/thermal/tmon/sysfs.c | |
| parent | b903036aad6c46f0c94b3a58c86f7467776a5dcf (diff) | |
| download | linux-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.c | 12 |
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; |