From ff7a0ea10d9607bed0cdc68cc02c59ee6367e8e2 Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Mon, 25 Nov 2013 18:35:48 +0000
Subject: [PATCH] Avoid runtime undefinedness due to integer overflow

Using TIMEVAL_MSEC_SUBTRACT can lead to integer overflow when the times
are far apart (such as epoch (0) or uninitialized timeval and "now").
Instead, calculate the "deadline" and use TIMEVAL_AFTER to test.
---
 scan_engine.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/scan_engine.cc b/scan_engine.cc
index b23b97e40..45d782f6a 100644
--- a/scan_engine.cc
+++ b/scan_engine.cc
@@ -1921,9 +1921,11 @@ int UltraScanInfo::removeCompletedHosts() {
   HostScanStats *hss = NULL;
   int hostsRemoved = 0;
   bool timedout = false;
+  struct timeval compare;
 
   /* We don't want to run this all of the time */
-  if ((unsigned) TIMEVAL_MSEC_SUBTRACT(now, lastCompletedHostRemoval) > completedHostLifetime / 2) {
+  TIMEVAL_MSEC_ADD(compare, lastCompletedHostRemoval, completedHostLifetime / 2);
+  if ( TIMEVAL_AFTER(now, compare) ) {
     for (hostI = completedHosts.begin(); hostI != completedHosts.end(); hostI = nxt) {
       nxt = hostI;
       nxt++;
@@ -1933,7 +1935,8 @@ int UltraScanInfo::removeCompletedHosts() {
       if (hss == gstats->pinghost)
         continue;
 
-      if ((unsigned) TIMEVAL_MSEC_SUBTRACT(now, hss->completiontime) > completedHostLifetime) {
+      TIMEVAL_MSEC_ADD(compare, hss->completiontime, completedHostLifetime);
+      if ( TIMEVAL_AFTER(now, compare) ) {
         completedHosts.erase(hostI);
         hostsRemoved++;
       }