Fix Integer-overflow in base::Time::FromExploded.

base/time/time_mac.cc

Index: base/time/time_mac.cc
diff --git a/base/time/time_mac.cc b/base/time/time_mac.cc
index 5803acd35117c175fc43067ac59ce880ee0197b2..88d2d4c28ee434420efe219c958bcb2fee29eceb 100644
--- a/base/time/time_mac.cc
+++ b/base/time/time_mac.cc
@@ -190,9 +190,18 @@ bool Time::FromExploded(bool is_local, const Exploded& exploded, Time* time) {
       exploded.millisecond);
   CFAbsoluteTime seconds = absolute_time + kCFAbsoluteTimeIntervalSince1970;
 
-  base::Time converted_time =
-      Time(static_cast<int64_t>(seconds * kMicrosecondsPerSecond) +
-           kWindowsEpochDeltaMicroseconds);
+  // CFAbsolutTime is typedef of double. Convert seconds to
+  // microseconds using this type and then cast to int64_t. If
+  // it cannot be suited to int64, then fail to avoid overflows.
+  CFAbsoluteTime microseconds =

[miu, 2016/10/18 19:55:13]

Even though we know CFAbsoluteTime is a double, it's not proper to use it here
because: 1) It is a data type whose timebase is in seconds; and 2) There's no
guarantee it won't be typedef'ed to something else in the future (though,
admittedly this is highly unlikely). So, please just use double here.

[maksims (do not use this acc), 2016/10/19 16:41:04]

Done.

+      (seconds * kMicrosecondsPerSecond) + kWindowsEpochDeltaMicroseconds;
+  if (microseconds > std::numeric_limits<int64_t>::max() ||
+      microseconds < std::numeric_limits<int64_t>::min()) {
+    *time = Time(0);
+    return false;
+  }
+
+  base::Time converted_time = Time(static_cast<int64_t>(microseconds));
 
   // If |exploded.day_of_month| is set to 31
   // on a 28-30 day month, it will return the first day of the next month.