Replace localtime() with localtime_r()

Since the result of localtime() is stored in a statically allocated
structure, data was overwritten when a context switch occurred during
(or shortly after) the execution of localtime(), potentially resulting
in critical data corruption. BUG#7 and BUG#8 are likely related.

This patch converts all usages of localtime() with localtime_r(), which
is thread-safe.

Reported-by: Baptiste Jonglez <baptiste@jonglez.org>
Reported-by: Erik Saule <esaule@bmi.osu.edu>
Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/notify.c b/src/notify.c
index a057c2f..10bc0f7 100644
--- a/src/notify.c
+++ b/src/notify.c
@@ -310,18 +310,18 @@ static void *notify_main_thread(void *arg)
   const unsigned check_app = MININSEC;
   int elapse = 0;
   int got_app;
-  struct tm *ntime;
+  struct tm ntime;
   time_t ntimer;
 
   elapse = 0;
 
   for (;;) {
     ntimer = time(NULL);
-    ntime = localtime(&ntimer);
+    localtime_r(&ntimer, &ntime);
     pthread_mutex_lock(&notify.mutex);
     pthread_mutex_lock(&nbar.mutex);
-    strftime(notify.time, NOTIFY_FIELD_LENGTH, nbar.timefmt, ntime);
-    strftime(notify.date, NOTIFY_FIELD_LENGTH, nbar.datefmt, ntime);
+    strftime(notify.time, NOTIFY_FIELD_LENGTH, nbar.timefmt, &ntime);
+    strftime(notify.date, NOTIFY_FIELD_LENGTH, nbar.datefmt, &ntime);
     pthread_mutex_unlock(&nbar.mutex);
     pthread_mutex_unlock(&notify.mutex);
     notify_update_bar();