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avformat/mxfdec: detect loops during header parsing 

The header parser uses forward and backward parsing, making the
bulletproof prevention of loops difficult, thus this simple
detection code.
If someone improves the forward/backward parsing so it cannot loop
then this commit should be reverted

Fixes Ticket3278

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2014-01-08 04:49:50 +01:00
parent 94cf4f8bac
commit 1c010fd035
1 changed files with 8 additions and 1 deletions
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9
libavformat/mxfdec.c
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@ -2011,6 +2011,8 @@ static int mxf_read_header(AVFormatContext *s)
MXFContext *mxf = s->priv_data;
KLVPacket klv;
int64_t essence_offset = 0;
int64_t last_pos = -1;
uint64_t last_pos_index = 1;
int ret;
mxf->last_forward_tell = INT64_MAX;
@ -2028,7 +2030,12 @@ static int mxf_read_header(AVFormatContext *s)
while (!url_feof(s->pb)) {
const MXFMetadataReadTableEntry *metadata;
if (avio_tell(s->pb) == last_pos) {
av_log(mxf->fc, AV_LOG_ERROR, "MXF structure loop detected\n");
return AVERROR_INVALIDDATA;
}
if ((1ULL<<61) % last_pos_index++ == 0)
last_pos = avio_tell(s->pb);
if (klv_read_packet(&klv, s->pb) < 0) {
/* EOF - seek to previous partition or stop */
if(mxf_parse_handle_partition_or_eof(mxf) <= 0)