libavformat/movenc.c:237: error: Null Dereference
  pointer `&gbc->buffer` last assigned on line 236 could be null and is dereferenced by call to `get_bits()` at line 237, column 18.

libavformat/movenc.c:223:1: start of procedure mov_write_ac3_tag()
221. }
222. 
223. static int mov_write_ac3_tag(ByteIOContext *pb, MOVTrack *track)
     ^
224. {
225.     GetBitContext gbc;

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

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

libavformat/movenc.c:234:5: Skipping put_tag(): empty list of specs
232. 
233.     put_be32(pb, 11);
234.     put_tag(pb, "dac3");
         ^
235. 
236.     init_get_bits(&gbc, track->vosData+4, track->vosLen-4);

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

libavcodec/bitstream.h:745:1: start of procedure init_get_bits()
  743.  * @param bit_size the size of the buffer in bits
  744.  */
  745. static inline void init_get_bits(GetBitContext *s,
       ^
  746.                    const uint8_t *buffer, int bit_size)
  747. {

libavcodec/bitstream.h:748:5: 
  746.                    const uint8_t *buffer, int bit_size)
  747. {
  748.     int buffer_size= (bit_size+7)>>3;
           ^
  749.     if(buffer_size < 0 || bit_size < 0) {
  750.         buffer_size = bit_size = 0;

libavcodec/bitstream.h:749:8: Taking true branch
  747. {
  748.     int buffer_size= (bit_size+7)>>3;
  749.     if(buffer_size < 0 || bit_size < 0) {
              ^
  750.         buffer_size = bit_size = 0;
  751.         buffer = NULL;

libavcodec/bitstream.h:750:9: 
  748.     int buffer_size= (bit_size+7)>>3;
  749.     if(buffer_size < 0 || bit_size < 0) {
  750.         buffer_size = bit_size = 0;
               ^
  751.         buffer = NULL;
  752.     }

libavcodec/bitstream.h:751:9: 
  749.     if(buffer_size < 0 || bit_size < 0) {
  750.         buffer_size = bit_size = 0;
  751.         buffer = NULL;
               ^
  752.     }
  753. 

libavcodec/bitstream.h:754:5: 
  752.     }
  753. 
  754.     s->buffer= buffer;
           ^
  755.     s->size_in_bits= bit_size;
  756.     s->buffer_end= buffer + buffer_size;

libavcodec/bitstream.h:755:5: 
  753. 
  754.     s->buffer= buffer;
  755.     s->size_in_bits= bit_size;
           ^
  756.     s->buffer_end= buffer + buffer_size;
  757. #ifdef ALT_BITSTREAM_READER

libavcodec/bitstream.h:756:5: 
  754.     s->buffer= buffer;
  755.     s->size_in_bits= bit_size;
  756.     s->buffer_end= buffer + buffer_size;
           ^
  757. #ifdef ALT_BITSTREAM_READER
  758.     s->index=0;

libavcodec/bitstream.h:758:5: 
  756.     s->buffer_end= buffer + buffer_size;
  757. #ifdef ALT_BITSTREAM_READER
  758.     s->index=0;
           ^
  759. #elif defined LIBMPEG2_BITSTREAM_READER
  760.     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));

libavcodec/bitstream.h:768:1: return from a call to init_get_bits
  766.     skip_bits_long(s, 0);
  767. #endif
  768. }
       ^
  769. 
  770. static inline void align_get_bits(GetBitContext *s)

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

libavcodec/bitstream.h:642:1: start of procedure get_bits()
  640.  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
  641.  */
  642. static inline unsigned int get_bits(GetBitContext *s, int n){
       ^
  643.     register int tmp;
  644.     OPEN_READER(re, s)

libavcodec/bitstream.h:644:5: 
  642. static inline unsigned int get_bits(GetBitContext *s, int n){
  643.     register int tmp;
  644.     OPEN_READER(re, s)
           ^
  645.     UPDATE_CACHE(re, s)
  646.     tmp= SHOW_UBITS(re, s, n);

libavcodec/bitstream.h:645:5: 
  643.     register int tmp;
  644.     OPEN_READER(re, s)
  645.     UPDATE_CACHE(re, s)
           ^
  646.     tmp= SHOW_UBITS(re, s, n);
  647.     LAST_SKIP_BITS(re, s, n)
