avformat/utils: avoid overflow in update_stream_timings() with huge durations

Fixes: usan_granule_overflow
Found-by: Thomas Guilbert <tguilbert@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/utils.c

@@ -2491,7 +2491,7 @@ static void update_stream_timings(AVFormatContext *ic)
             end_time1 = av_rescale_q_rnd(st->duration, st->time_base,
                                          AV_TIME_BASE_Q,
                                          AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
-            if (end_time1 != AV_NOPTS_VALUE) {
+            if (end_time1 != AV_NOPTS_VALUE && start_time1 <= INT64_MAX - end_time1) {
                 end_time1 += start_time1;
                 end_time = FFMAX(end_time, end_time1);
             }