On Sat, May 16, 2020 at 9:59 PM Andreas Rheinhardt <andreas.rheinha...@gmail.com> wrote: > > Mattias Wadman: > > lavf flacenc could previously write truncated metadata picture size if > > the picture data did not fit in 24 bits. Detect this by truncting the > > size found inside the picture block and if it matches the block size > > use it and read rest of picture data. > > > > Also only enable this workaround flac files and not ogg files with flac > > METADATA_BLOCK_PICTURE comment. > > > > flacenc was fixed in e447a4d112bcfee10126c54eb4481fa8712957c8 > > before the fix a broken flac for reproduction could be generated with: > > ffmpeg -f lavfi -i sine -f lavfi -i color=red:size=2400x2400 -map 0:0 -map > > 1:0 -c:v:0 bmp -disposition:1 attached_pic -t 1 test.flac > > > > Fixes ticket 6333 > > --- > > libavformat/flac_picture.c | 35 +++++++++++++++++++++++++++-------- > > libavformat/flac_picture.h | 2 +- > > libavformat/flacdec.c | 2 +- > > libavformat/oggparsevorbis.c | 2 +- > > 4 files changed, 30 insertions(+), 11 deletions(-) > > > > diff --git a/libavformat/flac_picture.c b/libavformat/flac_picture.c > > index 81ddf80465..61277e9dee 100644 > > --- a/libavformat/flac_picture.c > > +++ b/libavformat/flac_picture.c > > @@ -27,7 +27,7 @@ > > #include "id3v2.h" > > #include "internal.h" > > > > -int ff_flac_parse_picture(AVFormatContext *s, uint8_t *buf, int buf_size) > > +int ff_flac_parse_picture(AVFormatContext *s, uint8_t *buf, int buf_size, > > int truncate_workaround) > > { > > const CodecMime *mime = ff_id3v2_mime_tags; > > enum AVCodecID id = AV_CODEC_ID_NONE; > > @@ -36,7 +36,8 @@ int ff_flac_parse_picture(AVFormatContext *s, uint8_t > > *buf, int buf_size) > > GetByteContext g; > > AVStream *st; > > int width, height, ret = 0; > > - unsigned int len, type; > > + unsigned int type; > > + uint32_t len, left, trunclen = 0; > > > > if (buf_size < 34) { > > av_log(s, AV_LOG_ERROR, "Attached picture metadata block too > > short\n"); > > @@ -114,16 +115,34 @@ int ff_flac_parse_picture(AVFormatContext *s, uint8_t > > *buf, int buf_size) > > > > /* picture data */ > > len = bytestream2_get_be32u(&g); > > - if (len <= 0 || len > bytestream2_get_bytes_left(&g)) { > > - av_log(s, AV_LOG_ERROR, "Attached picture metadata block too > > short\n"); > > - if (s->error_recognition & AV_EF_EXPLODE) > > - ret = AVERROR_INVALIDDATA; > > - goto fail; > > + > > + left = bytestream2_get_bytes_left(&g); > > + if (len <= 0 || len > left) { > > + // Workaround lavf flacenc bug that allowed writing truncated > > metadata picture block size if > > I have not found the typical lavf metadata in the file from #6333, so it > seems we are not the only tool that created such out-of-spec files. This > should be reflected in the comment.
Good point, have been clarified. > > > + // picture size did not fit in 24 bits > > + if (truncate_workaround && len > left && (len & 0xffffff) == left) > > { > > There should be a way to disable this workaround; after all, there'd be > no remedy if the 32bit len field is bogus. Maybe check > strict_std_compliance for being >= FF_COMPLIANCE_STRICT. Fixed. Made it fail if strict level it above normal. > > > + av_log(s, AV_LOG_INFO, "Correcting truncated metadata picture > > size from %d to %d\n", left, len); > > + trunclen = len - left; > > + } else { > > + av_log(s, AV_LOG_ERROR, "Attached picture metadata block too > > short\n"); > > + if (s->error_recognition & AV_EF_EXPLODE) > > + ret = AVERROR_INVALIDDATA; > > + goto fail; > > + } > > } > > if (!(data = av_buffer_alloc(len + AV_INPUT_BUFFER_PADDING_SIZE))) { > > av_buffer_alloc() takes an int as its size argument. len + > AV_INPUT_BUFFER_PADDING_SIZE can be anything here; it can be positive or > negative. It can even be wrapped around. You need to check len for being > < INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE. I wonder whether it should not > be restricted even more (otherwise it would be easy to force an > allocation of close to 2GiB). Fixed. Fails if >500MB or INT_MAX overflow. > > > RETURN_ERROR(AVERROR(ENOMEM)); > > } > > - bytestream2_get_bufferu(&g, data->data, len); > > + > > + if (trunclen == 0) { > > + bytestream2_get_bufferu(&g, data->data, len); > > + } else { > > + // If truncation was detect copy all data from block and read > > missing bytes > > was detected Fixed. > > > + // not included in the block size > > + bytestream2_get_bufferu(&g, data->data, left); > > + if (avio_read(s->pb, data->data + len - trunclen, trunclen) < > > trunclen) > > + RETURN_ERROR(AVERROR_INVALIDDATA); > > + } > > memset(data->data + len, 0, AV_INPUT_BUFFER_PADDING_SIZE); > > > > if (AV_RB64(data->data) == PNGSIG) > > diff --git a/libavformat/flac_picture.h b/libavformat/flac_picture.h > > index 4374b6f4f6..61fd0c8806 100644 > > --- a/libavformat/flac_picture.h > > +++ b/libavformat/flac_picture.h > > @@ -26,6 +26,6 @@ > > > > #define RETURN_ERROR(code) do { ret = (code); goto fail; } while (0) > > > > -int ff_flac_parse_picture(AVFormatContext *s, uint8_t *buf, int buf_size); > > +int ff_flac_parse_picture(AVFormatContext *s, uint8_t *buf, int buf_size, > > int truncate_workaround); > > > > #endif /* AVFORMAT_FLAC_PICTURE_H */ > > diff --git a/libavformat/flacdec.c b/libavformat/flacdec.c > > index cb516fb1f3..79c05f14bf 100644 > > --- a/libavformat/flacdec.c > > +++ b/libavformat/flacdec.c > > @@ -146,7 +146,7 @@ static int flac_read_header(AVFormatContext *s) > > } > > av_freep(&buffer); > > } else if (metadata_type == FLAC_METADATA_TYPE_PICTURE) { > > - ret = ff_flac_parse_picture(s, buffer, metadata_size); > > + ret = ff_flac_parse_picture(s, buffer, metadata_size, 1); > > av_freep(&buffer); > > if (ret < 0) { > > av_log(s, AV_LOG_ERROR, "Error parsing attached > > picture.\n"); > > diff --git a/libavformat/oggparsevorbis.c b/libavformat/oggparsevorbis.c > > index 27d2c686b6..6f15204ada 100644 > > --- a/libavformat/oggparsevorbis.c > > +++ b/libavformat/oggparsevorbis.c > > @@ -165,7 +165,7 @@ int ff_vorbis_comment(AVFormatContext *as, AVDictionary > > **m, > > av_freep(&tt); > > av_freep(&ct); > > if (ret > 0) > > - ret = ff_flac_parse_picture(as, pict, ret); > > + ret = ff_flac_parse_picture(as, pict, ret, 0); > > av_freep(&pict); > > if (ret < 0) { > > av_log(as, AV_LOG_WARNING, "Failed to parse cover art > > block.\n"); > > > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".