libavformat/movenc.c:238: error: Null Dereference
  pointer `&gbc->buffer` last assigned on line 237 could be null and is dereferenced by call to `get_bits()` at line 238, column 18.

libavformat/movenc.c:224:1: start of procedure mov_write_ac3_tag()
222. }
223. 
224. static int mov_write_ac3_tag(ByteIOContext *pb, MOVTrack *track)
     ^
225. {
226.     GetBitContext gbc;

libavformat/movenc.c:231:9: Taking false branch
229.     int fscod, bsid, bsmod, acmod, lfeon, frmsizecod;
230. 
231.     if (track->vosLen < 7)
             ^
232.         return -1;
233. 

libavformat/movenc.c:234:5: Skipping put_be32(): empty list of specs
232.         return -1;
233. 
234.     put_be32(pb, 11);
         ^
235.     put_tag(pb, "dac3");
236. 

libavformat/movenc.c:235:5: Skipping put_tag(): empty list of specs
233. 
234.     put_be32(pb, 11);
235.     put_tag(pb, "dac3");
         ^
236. 
237.     init_get_bits(&gbc, track->vosData+4, track->vosLen-4);

libavformat/movenc.c:237:5: 
235.     put_tag(pb, "dac3");
236. 
237.     init_get_bits(&gbc, track->vosData+4, track->vosLen-4);
         ^
238.     fscod      = get_bits(&gbc, 2);
239.     frmsizecod = get_bits(&gbc, 6);

libavcodec/bitstream.h:737:1: start of procedure init_get_bits()
  735.  * @param bit_size the size of the buffer in bits
  736.  */
  737. static inline void init_get_bits(GetBitContext *s,
       ^
  738.                    const uint8_t *buffer, int bit_size)
  739. {

libavcodec/bitstream.h:740:5: 
  738.                    const uint8_t *buffer, int bit_size)
  739. {
  740.     int buffer_size= (bit_size+7)>>3;
           ^
  741.     if(buffer_size < 0 || bit_size < 0) {
  742.         buffer_size = bit_size = 0;

libavcodec/bitstream.h:741:8: Taking true branch
  739. {
  740.     int buffer_size= (bit_size+7)>>3;
  741.     if(buffer_size < 0 || bit_size < 0) {
              ^
  742.         buffer_size = bit_size = 0;
  743.         buffer = NULL;

libavcodec/bitstream.h:742:9: 
  740.     int buffer_size= (bit_size+7)>>3;
  741.     if(buffer_size < 0 || bit_size < 0) {
  742.         buffer_size = bit_size = 0;
               ^
  743.         buffer = NULL;
  744.     }

libavcodec/bitstream.h:743:9: 
  741.     if(buffer_size < 0 || bit_size < 0) {
  742.         buffer_size = bit_size = 0;
  743.         buffer = NULL;
               ^
  744.     }
  745. 

libavcodec/bitstream.h:746:5: 
  744.     }
  745. 
  746.     s->buffer= buffer;
           ^
  747.     s->size_in_bits= bit_size;
  748.     s->buffer_end= buffer + buffer_size;

libavcodec/bitstream.h:747:5: 
  745. 
  746.     s->buffer= buffer;
  747.     s->size_in_bits= bit_size;
           ^
  748.     s->buffer_end= buffer + buffer_size;
  749. #ifdef ALT_BITSTREAM_READER

libavcodec/bitstream.h:748:5: 
  746.     s->buffer= buffer;
  747.     s->size_in_bits= bit_size;
  748.     s->buffer_end= buffer + buffer_size;
           ^
  749. #ifdef ALT_BITSTREAM_READER
  750.     s->index=0;

libavcodec/bitstream.h:750:5: 
  748.     s->buffer_end= buffer + buffer_size;
  749. #ifdef ALT_BITSTREAM_READER
  750.     s->index=0;
           ^
  751. #elif defined LIBMPEG2_BITSTREAM_READER
  752.     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));

libavcodec/bitstream.h:760:1: return from a call to init_get_bits
  758.     skip_bits_long(s, 0);
  759. #endif
  760. }
       ^
  761. 
  762. static inline void align_get_bits(GetBitContext *s)

libavformat/movenc.c:238:5: 
236. 
237.     init_get_bits(&gbc, track->vosData+4, track->vosLen-4);
238.     fscod      = get_bits(&gbc, 2);
         ^
239.     frmsizecod = get_bits(&gbc, 6);
240.     bsid       = get_bits(&gbc, 5);

libavcodec/bitstream.h:634:1: start of procedure get_bits()
  632.  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
  633.  */
  634. static inline unsigned int get_bits(GetBitContext *s, int n){
       ^
  635.     register int tmp;
  636.     OPEN_READER(re, s)

libavcodec/bitstream.h:636:5: 
  634. static inline unsigned int get_bits(GetBitContext *s, int n){
  635.     register int tmp;
  636.     OPEN_READER(re, s)
           ^
  637.     UPDATE_CACHE(re, s)
  638.     tmp= SHOW_UBITS(re, s, n);

libavcodec/bitstream.h:637:5: 
  635.     register int tmp;
  636.     OPEN_READER(re, s)
  637.     UPDATE_CACHE(re, s)
           ^
  638.     tmp= SHOW_UBITS(re, s, n);
  639.     LAST_SKIP_BITS(re, s, n)
