[tor-commits] [tor/master] Add a safe guard to avoid using a zeroed voting schedule

[nickm at torproject.org]

commit e67f4441eb2646368e3e7cb1bcee403667b786f0
Author: David Goulet <dgoulet at torproject.org>
Date:   Tue Nov 7 11:14:45 2017 -0500

    Add a safe guard to avoid using a zeroed voting schedule
    
    dirvote_get_next_valid_after_time() is the only public function that uses the
    voting schedule outside of the dirvote subsystem so if it is zeroed,
    recalculate its timing if we can that is if a consensus exists.
    
    Part of #24161
    
    Signed-off-by: David Goulet <dgoulet at torproject.org>
---
 src/or/dirvote.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/or/dirvote.c b/src/or/dirvote.c
index c5ceefecb..33e5ea7d5 100644
--- a/src/or/dirvote.c
+++ b/src/or/dirvote.c
@@ -2859,6 +2859,13 @@ static voting_schedule_t voting_schedule;
 time_t
 dirvote_get_next_valid_after_time(void)
 {
+  /* This is a safe guard in order to make sure that the voting schedule
+   * static object is at least initialized. Using this function with a zeroed
+   * voting schedule can lead to bugs. */
+  if (tor_mem_is_zero((const char *) &voting_schedule,
+                      sizeof(voting_schedule))) {
+    dirvote_recalculate_timing(get_options(), time(NULL));
+  }
   return voting_schedule.interval_starts;
 }