src/sys/kern/kern_time.c - diff

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-version 1.161, 2009/09/13 18:45:11
+version 1.162, 2009/10/03 20:48:42
 Line 1461  timer_intr(void *cookie)
 Line 1461  timer_intr(void *cookie)
 Line 1461  timer_intr(void *cookie)
          mutex_spin_exit(&timer_lock);
          mutex_exit(proc_lock);
  }
+ /*
+  * Check if the time will wrap if set to ts.
+  *
+  * ts - timespec describing the new time
+  * delta - the delta between the current time and ts
+  */
+ bool
+ time_wraps(struct timespec *ts, struct timespec *delta)
+ {
+         /*
+          * Don't allow the time to be set forward so far it
+          * will wrap and become negative, thus allowing an
+          * attacker to bypass the next check below.  The
+          * cutoff is 1 year before rollover occurs, so even
+          * if the attacker uses adjtime(2) to move the time
+          * past the cutoff, it will take a very long time
+          * to get to the wrap point.
+          */
+         if ((ts->tv_sec > LLONG_MAX - 365*24*60*60) ||
+             (delta->tv_sec < 0 || delta->tv_nsec < 0))
+                 return true;
+         return false;
+ }