Fixes seek issue with ogg files that have segment data that happens to be
encoded as a "OggS" page syncword. Very unlikely but seems to happen.
Have been observed to happen with ffmpeg+libvorbis and oggenc encoding
to 441khz stereo at 160kbps.
---
libavformat/oggdec.c | 96 +++++++++++++++++++++++++++++++++-----------
1 file changed, 73 insertions(+), 23 deletions(-)
diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
index 95190589ab..22532f0341 100644
--- a/libavformat/oggdec.c
+++ b/libavformat/oggdec.c
@@ -31,6 +31,8 @@
#include <stdio.h>
#include "libavutil/avassert.h"
#include "libavutil/intreadwrite.h"
+#include "libavutil/crc.h"
+#include "libavcodec/bytestream.h"
#include "oggdec.h"
#include "avformat.h"
#include "internal.h"
@@ -339,14 +341,24 @@ static int ogg_read_page(AVFormatContext *s, int *sid)
AVIOContext *bc = s->pb;
struct ogg *ogg = s->priv_data;
struct ogg_stream *os;
- int ret, i = 0;
- int flags, nsegs;
+ int ret, i;
+ int version, flags, nsegs;
uint64_t gp;
uint32_t serial;
+ uint32_t crc;
int size, idx;
uint8_t sync[4];
- int sp = 0;
-
+ uint8_t header[23];
+ GetByteContext headergb;
+ uint8_t segments[255];
+ uint8_t *segmentsdata;
+ int sp;
+ const AVCRC *crc_table;
+ uint32_t ccrc;
+
+again:
+ sp = 0;
+ i = 0;
ret = avio_read(bc, sync, 4);
if (ret < 4)
return ret < 0 ? ret : AVERROR_EOF;
@@ -378,19 +390,59 @@ static int ogg_read_page(AVFormatContext *s, int *sid)
return AVERROR_INVALIDDATA;
}
- if (avio_r8(bc) != 0) { /* version */
- av_log (s, AV_LOG_ERROR, "ogg page, unsupported version\n");
+ ret = avio_read(bc, header, sizeof(header));
+ if (ret < sizeof(header))
+ return AVERROR_INVALIDDATA;
+ nsegs = header[22];
+ ret = avio_read(bc, segments, nsegs);
+ if (ret < nsegs)
+ return AVERROR_INVALIDDATA;
+ size = 0;
+ for (i = 0; i < nsegs; i++)
+ size += segments[i];
+
+ bytestream2_init(&headergb, header, sizeof(header));
+ version = bytestream2_get_byte(&headergb);
+ flags = bytestream2_get_byte(&headergb);
+ gp = bytestream2_get_le64(&headergb);
+ serial = bytestream2_get_le32(&headergb);
+ bytestream2_skip(&headergb, 4); // seq le32
+ crc = bytestream2_get_le32(&headergb);
+
+ segmentsdata = av_malloc(size);
+ if (!segmentsdata)
+ return AVERROR(ENOMEM);
+ ret = avio_read(bc, segmentsdata, size);
+ if (ret < size) {
+ av_freep(&segmentsdata);
return AVERROR_INVALIDDATA;
}
- flags = avio_r8(bc);
- gp = avio_rl64(bc);
- serial = avio_rl32(bc);
- avio_skip(bc, 8); /* seq, crc */
- nsegs = avio_r8(bc);
+ // Reset CRC in header to zero and calculate for whole page
+ crc_table = av_crc_get_table(AV_CRC_32_IEEE);
+ memset(&header[18], 0, 4);
+ ccrc = 0;
+ ccrc = av_crc(crc_table, ccrc, "OggS", 4);
+ ccrc = av_crc(crc_table, ccrc, header, sizeof(header));
+ ccrc = av_crc(crc_table, ccrc, segments, nsegs);
+ ccrc = av_crc(crc_table, ccrc, segmentsdata, size);
+ // Default AV_CRC_32_IEEE table is BE
+ ccrc = av_bswap32(ccrc);
+
+ if (ccrc != crc) {
+ av_log(s, AV_LOG_TRACE, "ogg page, invalid checksum %x != %x\n", ccrc,
crc);
+ if (s->error_recognition & AV_EF_CRCCHECK) {
+ av_freep(&segmentsdata);
+ // TODO: smarter use of read data?
+ goto again;
+ }
+ }
- if (avio_feof(bc))
- return AVERROR_EOF;
+ if (version != 0) {
+ av_log(s, AV_LOG_ERROR, "ogg page, unsupported version %d\n", version);
+ av_freep(&segmentsdata);
+ return AVERROR_INVALIDDATA;
+ }
idx = ogg_find_stream(ogg, serial);
if (idx < 0) {
@@ -401,24 +453,24 @@ static int ogg_read_page(AVFormatContext *s, int *sid)
if (idx < 0) {
av_log(s, AV_LOG_ERROR, "failed to create or replace stream\n");
+ av_freep(&segmentsdata);
return idx;
}
}
os = ogg->streams + idx;
ogg->page_pos =
- os->page_pos = avio_tell(bc) - 27;
+ os->page_pos = avio_tell(bc) - 27 - size - nsegs;;
if (os->psize > 0) {
ret = ogg_new_buf(ogg, idx);
- if (ret < 0)
+ if (ret < 0) {
+ av_freep(&segmentsdata);
return ret;
+ }
}
- ret = avio_read(bc, os->segments, nsegs);
- if (ret < nsegs)
- return ret < 0 ? ret : AVERROR_EOF;
-
+ memcpy(os->segments, segments, nsegs);
os->nsegs = nsegs;
os->segp = 0;
@@ -456,10 +508,8 @@ static int ogg_read_page(AVFormatContext *s, int *sid)
os->buf = nb;
}
- ret = avio_read(bc, os->buf + os->bufpos, size);
- if (ret < size)
- return ret < 0 ? ret : AVERROR_EOF;
-
+ memcpy(os->buf + os->bufpos, segmentsdata, size);
+ av_freep(&segmentsdata);
os->bufpos += size;
os->granule = gp;
os->flags = flags;
--
2.18.0
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