[FFmpeg-cvslog] avformat/utils: Check dts - (1<<pts_wrap_bits) overflow

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Jan 14 21:29:01 2021 +0100| [d82ee907d6caafbc1212c4b63ecac2dcd30f23b0] | committer: Michael Niedermayer

avformat/utils: Check dts - (1<<pts_wrap_bits) overflow

Fixes: signed integer overflow: -9223372036842389247 - 2147483648 cannot be represented in type 'long long'
Fixes: 26910/clusterfuzz-testcase-minimized-ffmpeg_dem_FLV_fuzzer-4845007531671552

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d82ee907d6caafbc1212c4b63ecac2dcd30f23b0
---

 libavformat/utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/utils.c b/libavformat/utils.c
index f534b6e5b5..6f100294a1 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1254,7 +1254,7 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
         presentation_delayed = 1;
 
     if (pkt->pts != AV_NOPTS_VALUE && pkt->dts != AV_NOPTS_VALUE &&
-        st->pts_wrap_bits < 63 &&
+        st->pts_wrap_bits < 63 && pkt->dts > INT64_MIN + (1LL << (st->pts_wrap_bits - 1)) &&
         pkt->dts - (1LL << (st->pts_wrap_bits - 1)) > pkt->pts) {
         if (is_relative(st->cur_dts) || pkt->dts - (1LL<<(st->pts_wrap_bits - 1)) > st->cur_dts) {
             pkt->dts -= 1LL << st->pts_wrap_bits;