[FFmpeg-cvslog] avformat/mov: Check a.size before computing next_root_atom

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Nov 28 21:20:43 2020 +0100| [8c9a5a0fe9f27be35332a2b8f604dc85d219a056] | committer: Michael Niedermayer

avformat/mov: Check a.size before computing next_root_atom

Fixes: signed integer overflow: 64 + 9223372036854775799 cannot be represented in type 'long'
Fixes: 27563/clusterfuzz-testcase-minimized-ffmpeg_dem_MOV_fuzzer-6244650163372032

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=8c9a5a0fe9f27be35332a2b8f604dc85d219a056
---

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

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 3215b53636..ad0b9a58d3 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -7071,7 +7071,7 @@ static int mov_read_default(MOVContext *c, AVIOContext *pb, MOVAtom atom)
                 c->atom_depth --;
                 return err;
             }
-            if (c->found_moov && c->found_mdat &&
+            if (c->found_moov && c->found_mdat && a.size <= INT64_MAX - start_pos &&
                 ((!(pb->seekable & AVIO_SEEKABLE_NORMAL) || c->fc->flags & AVFMT_FLAG_IGNIDX || c->frag_index.complete) ||
                  start_pos + a.size == avio_size(pb))) {
                 if (!(pb->seekable & AVIO_SEEKABLE_NORMAL) || c->fc->flags & AVFMT_FLAG_IGNIDX || c->frag_index.complete)