[FFmpeg-cvslog] avformat/bfi: Check offsets better

Michael Niedermayer git at videolan.org
Sun Oct 9 23:06:10 EEST 2022


ffmpeg | branch: release/4.2 | Michael Niedermayer <michael at niedermayer.cc> | Sun Mar 20 23:24:40 2022 +0100| [a162f52438d585f4e8f3580ec3d174dad0ef8f6d] | committer: Michael Niedermayer

avformat/bfi: Check offsets better

Fixes: signed integer overflow: -2145378272 - 538976288 cannot be represented in type 'int'
Fixes: 45690/clusterfuzz-testcase-minimized-ffmpeg_IO_DEMUXER_fuzzer-5015496544616448

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 35dc93ab44a57d78956414624c4e011414220e98)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a162f52438d585f4e8f3580ec3d174dad0ef8f6d
---

 libavformat/bfi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavformat/bfi.c b/libavformat/bfi.c
index f9e0bb2e30..35b6816aad 100644
--- a/libavformat/bfi.c
+++ b/libavformat/bfi.c
@@ -140,12 +140,12 @@ static int bfi_read_packet(AVFormatContext * s, AVPacket * pkt)
         audio_offset    = avio_rl32(pb);
         avio_rl32(pb);
         video_offset    = avio_rl32(pb);
-        audio_size      = video_offset - audio_offset;
-        bfi->video_size = chunk_size - video_offset;
-        if (audio_size < 0 || bfi->video_size < 0) {
+        if (audio_offset < 0 || video_offset < audio_offset || chunk_size < video_offset) {
             av_log(s, AV_LOG_ERROR, "Invalid audio/video offsets or chunk size\n");
             return AVERROR_INVALIDDATA;
         }
+        audio_size      = video_offset - audio_offset;
+        bfi->video_size = chunk_size - video_offset;
 
         //Tossing an audio packet at the audio decoder.
         ret = av_get_packet(pb, pkt, audio_size);



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