[FFmpeg-devel] [PATCH] avformat/mxfdec: Fix false positive in infinite loop detector

[Michael Niedermayer]

Fixes Ticket4040

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
---
 libavformat/mxfdec.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index b01dd0c..a1abc34 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -2211,6 +2211,13 @@ end:
     avio_seek(s->pb, mxf->run_in, SEEK_SET);
 }
 
+static uint64_t loop_detection_state(AVFormatContext *s)
+{
+    MXFContext *mxf = s->priv_data;
+
+    return avio_tell(s->pb) + 0xA987654321*!mxf->current_partition;
+}
+
 static int mxf_read_header(AVFormatContext *s)
 {
     MXFContext *mxf = s->priv_data;
@@ -2235,12 +2242,12 @@ static int mxf_read_header(AVFormatContext *s)
 
     while (!avio_feof(s->pb)) {
         const MXFMetadataReadTableEntry *metadata;
-        if (avio_tell(s->pb) == last_pos) {
+        if (loop_detection_state(s) == 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);
+            last_pos = loop_detection_state(s);
         if (klv_read_packet(&klv, s->pb) < 0) {
             /* EOF - seek to previous partition or stop */
             if(mxf_parse_handle_partition_or_eof(mxf) <= 0)
-- 
1.7.9.5