Fix more integer underflow cases in base::Time::FromExploded.

base/time/time_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/time/time.h"
 
 #include <stdint.h>
 #include <sys/time.h>
 #include <time.h>
 #if defined(OS_ANDROID) && !defined(__LP64__)
 #include <time64.h>
 #endif
 #include <unistd.h>
 
 #include <limits>
 #include <ostream>
 
 #include "base/logging.h"
+#include "base/numerics/safe_math.h"
 #include "build/build_config.h"
 
 #if defined(OS_ANDROID)
 #include "base/os_compat_android.h"
 #elif defined(OS_NACL)
 #include "base/os_compat_nacl.h"
 #endif
 
 #if !defined(OS_MACOSX)
 #include "base/lazy_instance.h"
@@ skipping 191 matching lines @@
   exploded->day_of_week  = timestruct.tm_wday;
   exploded->day_of_month = timestruct.tm_mday;
   exploded->hour         = timestruct.tm_hour;
   exploded->minute       = timestruct.tm_min;
   exploded->second       = timestruct.tm_sec;
   exploded->millisecond  = millisecond;
 }
 
 // static
 bool Time::FromExploded(bool is_local, const Exploded& exploded, Time* time) {
+  CheckedNumeric<int> month = exploded.month;
+  month--;
+  CheckedNumeric<int> year = exploded.year;
+  year -= 1900;
+  if (!month.IsValid() || !year.IsValid()) {
+    *time = Time(0);
+    return false;
+  }
+
   struct tm timestruct;
-  timestruct.tm_sec    = exploded.second;
-  timestruct.tm_min    = exploded.minute;
-  timestruct.tm_hour   = exploded.hour;
-  timestruct.tm_mday   = exploded.day_of_month;
-  timestruct.tm_mon    = exploded.month - 1;
-  timestruct.tm_year   = exploded.year - 1900;
-  timestruct.tm_wday   = exploded.day_of_week;  // mktime/timegm ignore this
-  timestruct.tm_yday   = 0;     // mktime/timegm ignore this
-  timestruct.tm_isdst  = -1;    // attempt to figure it out
+  timestruct.tm_sec = exploded.second;
+  timestruct.tm_min = exploded.minute;
+  timestruct.tm_hour = exploded.hour;
+  timestruct.tm_mday = exploded.day_of_month;
+  timestruct.tm_mon = month.ValueOrDie();
+  timestruct.tm_year = year.ValueOrDie();
+  timestruct.tm_wday = exploded.day_of_week;  // mktime/timegm ignore this
+  timestruct.tm_yday = 0;                     // mktime/timegm ignore this
+  timestruct.tm_isdst = -1;                   // attempt to figure it out
 #if !defined(OS_NACL) && !defined(OS_SOLARIS)
-  timestruct.tm_gmtoff = 0;     // not a POSIX field, so mktime/timegm ignore
-  timestruct.tm_zone   = NULL;  // not a POSIX field, so mktime/timegm ignore
+  timestruct.tm_gmtoff = 0;   // not a POSIX field, so mktime/timegm ignore
+  timestruct.tm_zone = NULL;  // not a POSIX field, so mktime/timegm ignore
 #endif
 
   SysTime seconds;
 
   // Certain exploded dates do not really exist due to daylight saving times,
   // and this causes mktime() to return implementation-defined values when
   // tm_isdst is set to -1. On Android, the function will return -1, while the
   // C libraries of other platforms typically return a liberally-chosen value.
   // Handling this requires the special code below.
 
@@ skipping 156 matching lines @@
     result.tv_usec = static_cast<suseconds_t>(Time::kMicrosecondsPerSecond) - 1;
     return result;
   }
   int64_t us = us_ - kTimeTToMicrosecondsOffset;
   result.tv_sec = us / Time::kMicrosecondsPerSecond;
   result.tv_usec = us % Time::kMicrosecondsPerSecond;
   return result;
 }
 
 }  // namespace base