mxfdec: avoid double free and leaks.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/mxfdec.c

@@ -240,6 +240,8 @@ typedef struct {
     enum MXFMetadataSetType type;
 } MXFMetadataReadTableEntry;
 
+static int mxf_read_close(AVFormatContext *s);
+
 /* partial keys to match */
 static const uint8_t mxf_header_partition_pack_key[]       = { 0x06,0x0e,0x2b,0x34,0x02,0x05,0x01,0x01,0x0d,0x01,0x02,0x01,0x01,0x02 };
 static const uint8_t mxf_essence_element_key[]             = { 0x06,0x0e,0x2b,0x34,0x01,0x02,0x01,0x01,0x0d,0x01,0x03,0x01 };
@@ -1930,10 +1932,10 @@ static int mxf_read_header(AVFormatContext *s)
     /* we need to do this before computing the index tables
      * to be able to fill in zero IndexDurations with st->duration */
     if ((ret = mxf_parse_structural_metadata(mxf)) < 0)
-        return ret;
+        goto fail;
 
     if ((ret = mxf_compute_index_tables(mxf)) < 0)
-        return ret;
+        goto fail;
 
     if (mxf->nb_index_tables > 1) {
         /* TODO: look up which IndexSID to use via EssenceContainerData */
@@ -1941,12 +1943,17 @@ static int mxf_read_header(AVFormatContext *s)
                mxf->nb_index_tables, mxf->index_tables[0].index_sid);
     } else if (mxf->nb_index_tables == 0 && mxf->op == OPAtom) {
         av_log(mxf->fc, AV_LOG_ERROR, "cannot demux OPAtom without an index\n");
-        return AVERROR_INVALIDDATA;
+        ret = AVERROR_INVALIDDATA;
+        goto fail;
     }
 
     mxf_handle_small_eubc(s);
 
     return 0;
+fail:
+    mxf_read_close(s);
+
+    return ret;
 }
 
 /**