avformat/utils: Check start/end before computing duration in update_stream_timings()

Fixes undefined behavior
Fixes: 637428.ogg
Found-by: Matt Wolenetz <wolenetz@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/utils.c

@@ -2597,13 +2597,16 @@ static void update_stream_timings(AVFormatContext *ic)
             if (ic->nb_programs > 1) {
                 for (i = 0; i < ic->nb_programs; i++) {
                     p = ic->programs[i];
-                    if (p->start_time != AV_NOPTS_VALUE && p->end_time > p->start_time)
+                    if (p->start_time != AV_NOPTS_VALUE &&
+                        p->end_time > p->start_time &&
+                        p->end_time - (uint64_t)p->start_time <= INT64_MAX)
                         duration = FFMAX(duration, p->end_time - p->start_time);
                 }
-            } else
+            } else if (end_time >= start_time && end_time - (uint64_t)start_time <= INT64_MAX) {
                 duration = FFMAX(duration, end_time - start_time);
             }
         }
+    }
     if (duration != INT64_MIN && duration > 0 && ic->duration == AV_NOPTS_VALUE) {
         ic->duration = duration;
     }