[FFmpeg-devel] [PATCH 2/4] avformat/vividas: Check that value from ffio_read_varlen() does not overflow

[Michael Niedermayer]

Fixes: signed integer overflow: -1241665686 + -1340629419 cannot be represented in type 'int'
Fixes: 15922/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5692826442006528

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavformat/vividas.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libavformat/vividas.c b/libavformat/vividas.c
index 1895c75858..c3d3cf548c 100644
--- a/libavformat/vividas.c
+++ b/libavformat/vividas.c
@@ -374,8 +374,11 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s,  uint8_t *
             ffio_read_varlen(pb); // len_3
             num_data = avio_r8(pb);
             for (j = 0; j < num_data; j++) {
-                data_len[j] = ffio_read_varlen(pb);
-                xd_size += data_len[j];
+                uint64_t len = ffio_read_varlen(pb);
+                if (len > INT_MAX/2 - xd_size)
+                    return AVERROR_INVALIDDATA;
+                data_len[j] = len;
+                xd_size += len;
             }
 
             st->codecpar->extradata_size = 64 + xd_size + xd_size / 255;
-- 
2.22.0