On Sun, Oct 27, 2019 at 10:06:11PM +0100, Mattias Wadman wrote:
> Think i messed up the formatting of the in-line patch somehow. Ill send the
> patch as an attachment instead. Hope reply and attach is ok?
>
> On Sun, Oct 27, 2019 at 8:22 PM Mattias Wadman <mattias.wad...@gmail.com>
> wrote:
>
> > A too big picture will case the muxer to write a truncated block size
> > (uint24)
> > causing the output file to be corrupt.
> >
> > How to reproduce:
> >
> > Write a file with truncated block size:
> > ffmpeg -y -f lavfi -i sine -f lavfi -i color=red:size=2400x2400 -map 0:a:0
> > -map 1:v:0 -c:v:0 bmp -disposition:1 attached_pic -t 1 test.flac
> >
> > Try to decode:
> > ffmpeg -i test.flac test.wav
> >
> > Signed-off-by: Mattias Wadman <mattias.wad...@gmail.com>
> > ---
> > libavformat/flacenc.c | 10 ++++++++--
> > 1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git libavformat/flacenc.c libavformat/flacenc.c
> > index 93cc79bbe0..957bcb1123 100644
> > --- libavformat/flacenc.c
> > +++ libavformat/flacenc.c
> > @@ -93,7 +93,7 @@ static int flac_write_picture(struct AVFormatContext *s,
> > AVPacket *pkt)
> > AVDictionaryEntry *e;
> > const char *mimetype = NULL, *desc = "";
> > const AVStream *st = s->streams[pkt->stream_index];
> > - int i, mimelen, desclen, type = 0;
> > + int i, mimelen, desclen, type = 0, blocklen = 0;
> >
> > if (!pkt->data)
> > return 0;
> > @@ -140,8 +140,14 @@ static int flac_write_picture(struct AVFormatContext
> > *s, AVPacket *pkt)
> > desc = e->value;
> > desclen = strlen(desc);
> >
> > + blocklen = 4 + 4 + mimelen + 4 + desclen + 4 + 4 + 4 + 4 + 4 +
> > pkt->size;
> > + if (blocklen >= 1<<24) {
> > + av_log(s, AV_LOG_ERROR, "Picture block too big %d >= %d\n",
> > blocklen, 1<<24);
> > + return AVERROR(EINVAL);
> > + }
> > +
> > avio_w8(pb, 0x06);
> > - avio_wb24(pb, 4 + 4 + mimelen + 4 + desclen + 4 + 4 + 4 + 4 + 4 +
> > pkt->size);
> > + avio_wb24(pb, blocklen);
> >
> > avio_wb32(pb, type);
> >
> > --
> > 2.22.0
> >> flacenc.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > 4b8ce8290f9727383c669467ba5c8358ac12b156 > 0001-libavformat-flacenc-reject-too-large-picture-blocks.patch > From ea7cfb4fde056fbfdc9c7970453176281a16df27 Mon Sep 17 00:00:00 2001 > From: Mattias Wadman <mattias.wad...@gmail.com> > Date: Sun, 27 Oct 2019 20:00:06 +0100 > Subject: [PATCH] libavformat/flacenc: reject too large picture blocks > > A large picture will case the muxer to write a truncated block size (uint24) > causing the output file to be corrupt. > > How to reproduce: > > Write a file with truncated block size: > ffmpeg -y -f lavfi -i sine -f lavfi -i color=red:size=2400x2400 -map 0:a:0 > -map 1:v:0 -c:v:0 bmp -disposition:1 attached_pic -t 1 test.flac > > Try to decode: > ffmpeg -i test.flac test.wav > > Signed-off-by: Mattias Wadman <mattias.wad...@gmail.com> > --- > libavformat/flacenc.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git libavformat/flacenc.c libavformat/flacenc.c > index 93cc79bbe0..957bcb1123 100644 > --- libavformat/flacenc.c > +++ libavformat/flacenc.c > @@ -93,7 +93,7 @@ static int flac_write_picture(struct AVFormatContext *s, > AVPacket *pkt) > AVDictionaryEntry *e; > const char *mimetype = NULL, *desc = ""; > const AVStream *st = s->streams[pkt->stream_index]; > - int i, mimelen, desclen, type = 0; > + int i, mimelen, desclen, type = 0, blocklen = 0; The initialization to 0 is useless [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB "You are 36 times more likely to die in a bathtub than at the hands of a terrorist. Also, you are 2.5 times more likely to become a president and 2 times more likely to become an astronaut, than to die in a terrorist attack." -- Thoughty2
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