avformat/concatdec: Check in and outpoints to be to produce a positive representable duration

Fixes: signed integer overflow: -93000000 - 9223372036839000000 cannot be represented in type 'long'
Fixes: 64546/clusterfuzz-testcase-minimized-ffmpeg_dem_CONCAT_fuzzer-5110813828186112

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/concatdec.c

@@ -638,6 +638,12 @@ static int concat_parse_script(AVFormatContext *avf)
         }
     }
 
+    if (file->inpoint != AV_NOPTS_VALUE && file->outpoint != AV_NOPTS_VALUE) {
+        if (file->inpoint  > file->outpoint ||
+            file->outpoint - (uint64_t)file->inpoint > INT64_MAX)
+            ret = AVERROR_INVALIDDATA;
+    }
+
 fail:
     for (arg = 0; arg < MAX_ARGS; arg++)
         av_freep(&arg_str[arg]);