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| author | Andreas Rheinhardt <andreas.rheinhardt@outlook.com> | 2022-01-15 07:43:03 +0100 |
|---|---|---|
| committer | Andreas Rheinhardt <andreas.rheinhardt@outlook.com> | 2022-01-19 11:22:34 +0100 |
| commit | 5e186f9693db11dc720afa867659afee978b02d8 (patch) | |
| tree | 36b27bdc0fb9653d91aa3c1124f882700b7dd271 /libavformat | |
| parent | ca168635494276bb7f2f686de07747e7f493e30c (diff) | |
| download | ffmpeg-5e186f9693db11dc720afa867659afee978b02d8.tar.gz | |
avformat/matroskaenc: Don't open BlockGroup twice
This would happen in case non-WebVTT-subtitles had BlockAdditional
or DiscardPadding side-data. Given that these are not accounted for
in the length of the outer BlockGroup (which is a quite sharp upper
bound) it is possible for the outer BlockGroup to use an insufficient
number of bytes which leads to an assert in end_ebml_master().
Fix this by not opening a second BlockGroup inside an already opened
BlockGroup.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Diffstat (limited to 'libavformat')
| -rw-r--r-- | libavformat/matroskaenc.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c index 1dde12a7d9..81194fd28d 100644 --- a/libavformat/matroskaenc.c +++ b/libavformat/matroskaenc.c @@ -2095,6 +2095,7 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb, int64_t discard_padding = 0; unsigned track_number = track->track_num; ebml_master block_group, block_additions, block_more; + int blockgroup_already_opened = blockid == MATROSKA_ID_BLOCK; ts += track->ts_offset; @@ -2141,7 +2142,7 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb, side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_SKIP_SAMPLES, &side_data_size); - if (side_data && side_data_size >= 10) { + if (side_data && side_data_size >= 10 && !blockgroup_already_opened) { discard_padding = av_rescale_q(AV_RL32(side_data + 4), (AVRational){1, par->sample_rate}, (AVRational){1, 1000000000}); @@ -2152,7 +2153,8 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb, &side_data_size); if (side_data) { // Only the Codec-specific BlockMore (id == 1) is currently supported. - if (side_data_size < 8 || (additional_id = AV_RB64(side_data)) != 1) { + if (side_data_size < 8 || (additional_id = AV_RB64(side_data)) != 1 || + blockgroup_already_opened) { side_data_size = 0; } else { side_data += 8; |