From 1c010fd035c1a14dc73827b84f21f593e969a5d6 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Wed, 8 Jan 2014 04:49:50 +0100 Subject: [PATCH] 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 --- libavformat/mxfdec.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c index 61c0cb2366..07740ebb4b 100644 --- a/libavformat/mxfdec.c +++ b/libavformat/mxfdec.c @@ -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)