libavcodec/vp3.c:1818: error: Null Dereference
  pointer `&gb->buffer` last assigned on line 1810 could be null and is dereferenced by call to `get_bits1()` at line 1818, column 20.

libavcodec/vp3.c:1801:1: start of procedure vp3_decode_frame()
1799.  * This is the ffmpeg/libavcodec API frame decode function.
1800.  */
1801. static int vp3_decode_frame(AVCodecContext *avctx,
      ^
1802.                             void *data, int *data_size,
1803.                             const uint8_t *buf, int buf_size)

libavcodec/vp3.c:1805:5: 
1803.                             const uint8_t *buf, int buf_size)
1804. {
1805.     Vp3DecodeContext *s = avctx->priv_data;
          ^
1806.     GetBitContext gb;
1807.     static int counter = 0;

libavcodec/vp3.c:1807:5: 
1805.     Vp3DecodeContext *s = avctx->priv_data;
1806.     GetBitContext gb;
1807.     static int counter = 0;
          ^
1808.     int i;
1809. 

libavcodec/vp3.c:1810:5: 
1808.     int i;
1809. 
1810.     init_get_bits(&gb, buf, buf_size * 8);
          ^
1811. 
1812.     if (s->theora && get_bits1(&gb))

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)

libavcodec/vp3.c:1812:9: Taking false branch
1810.     init_get_bits(&gb, buf, buf_size * 8);
1811. 
1812.     if (s->theora && get_bits1(&gb))
              ^
1813.     {
1814.         av_log(avctx, AV_LOG_ERROR, "Header packet passed to frame decoder, skipping\n");

libavcodec/vp3.c:1818:20: 
1816.     }
1817. 
1818.     s->keyframe = !get_bits1(&gb);
                         ^
1819.     if (!s->theora)
1820.         skip_bits(&gb, 1);

libavcodec/bitstream.h:665:1: start of procedure get_bits1()
  663. }
  664. 
  665. static inline unsigned int get_bits1(GetBitContext *s){
       ^
  666. #ifdef ALT_BITSTREAM_READER
  667.     int index= s->index;

libavcodec/bitstream.h:667:5: 
  665. static inline unsigned int get_bits1(GetBitContext *s){
  666. #ifdef ALT_BITSTREAM_READER
  667.     int index= s->index;
           ^
  668.     uint8_t result= s->buffer[ index>>3 ];
  669. #ifdef ALT_BITSTREAM_READER_LE

libavcodec/bitstream.h:668:5: 
  666. #ifdef ALT_BITSTREAM_READER
  667.     int index= s->index;
  668.     uint8_t result= s->buffer[ index>>3 ];
           ^
  669. #ifdef ALT_BITSTREAM_READER_LE
  670.     result>>= (index&0x07);
