Fix fairly harmless OOB read from MAV_0001.3G2.asan.4f.188

source/patched-ffmpeg/libavformat/mov.c

 /*
  * MOV demuxer
  * Copyright (c) 2001 Fabrice Bellard
  * Copyright (c) 2009 Baptiste Coudurier <baptiste dot coudurier at gmail dot com>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
@@ skipping 1540 matching lines @@
         }
     }
 
     /* only use old uncompressed audio chunk demuxing when stts specifies it */
     if (!(st->codec->codec_type == AVMEDIA_TYPE_AUDIO &&
           sc->stts_count == 1 && sc->stts_data[0].duration == 1)) {
         unsigned int current_sample = 0;
         unsigned int stts_sample = 0;
         unsigned int sample_size;
         unsigned int distance = 0;
-        int key_off = sc->keyframes && sc->keyframes[0] == 1;
+        int key_off = sc->keyframe_count && sc->keyframes[0] == 1;
 
         current_dts -= sc->dts_shift;
 
         if (sc->sample_count >= UINT_MAX / sizeof(*st->index_entries))
             return;
         st->index_entries = av_malloc(sc->sample_count*sizeof(*st->index_entries));
         if (!st->index_entries)
             return;
         st->index_entries_allocated_size = sc->sample_count*sizeof(*st->index_entries);
 
@@ skipping 1060 matching lines @@
 AVInputFormat ff_mov_demuxer = {
     "mov,mp4,m4a,3gp,3g2,mj2",
     NULL_IF_CONFIG_SMALL("QuickTime/MPEG-4/Motion JPEG 2000 format"),
     sizeof(MOVContext),
     mov_probe,
     mov_read_header,
     mov_read_packet,
     mov_read_close,
     mov_read_seek,
 };