libavcodec/vp3.c:2144: error: Null Dereference
  pointer `&gb->buffer` last assigned on line 2136 could be null and is dereferenced by call to `get_bits1()` at line 2144, column 20.

libavcodec/vp3.c:2127:1: start of procedure vp3_decode_frame()
2125.  * This is the ffmpeg/libavcodec API frame decode function.
2126.  */
2127. static int vp3_decode_frame(AVCodecContext *avctx,
      ^
2128.                             void *data, int *data_size,
2129.                             const uint8_t *buf, int buf_size)

libavcodec/vp3.c:2131:5: 
2129.                             const uint8_t *buf, int buf_size)
2130. {
2131.     Vp3DecodeContext *s = avctx->priv_data;
          ^
2132.     GetBitContext gb;
2133.     static int counter = 0;

libavcodec/vp3.c:2133:5: 
2131.     Vp3DecodeContext *s = avctx->priv_data;
2132.     GetBitContext gb;
2133.     static int counter = 0;
          ^
2134.     int i;
2135. 

libavcodec/vp3.c:2136:5: 
2134.     int i;
2135. 
2136.     init_get_bits(&gb, buf, buf_size * 8);
          ^
2137. 
2138.     if (s->theora && get_bits1(&gb))

libavcodec/bitstream.h:758:1: start of procedure init_get_bits()
  756.  * @param bit_size the size of the buffer in bits
  757.  */
  758. static inline void init_get_bits(GetBitContext *s,
       ^
  759.                    const uint8_t *buffer, int bit_size)
  760. {

libavcodec/bitstream.h:761:5: 
  759.                    const uint8_t *buffer, int bit_size)
  760. {
  761.     int buffer_size= (bit_size+7)>>3;
           ^
  762.     if(buffer_size < 0 || bit_size < 0) {
  763.         buffer_size = bit_size = 0;

libavcodec/bitstream.h:762:8: Taking true branch
  760. {
  761.     int buffer_size= (bit_size+7)>>3;
  762.     if(buffer_size < 0 || bit_size < 0) {
              ^
  763.         buffer_size = bit_size = 0;
  764.         buffer = NULL;

libavcodec/bitstream.h:763:9: 
  761.     int buffer_size= (bit_size+7)>>3;
  762.     if(buffer_size < 0 || bit_size < 0) {
  763.         buffer_size = bit_size = 0;
               ^
  764.         buffer = NULL;
  765.     }

libavcodec/bitstream.h:764:9: 
  762.     if(buffer_size < 0 || bit_size < 0) {
  763.         buffer_size = bit_size = 0;
  764.         buffer = NULL;
               ^
  765.     }
  766. 

libavcodec/bitstream.h:767:5: 
  765.     }
  766. 
  767.     s->buffer= buffer;
           ^
  768.     s->size_in_bits= bit_size;
  769.     s->buffer_end= buffer + buffer_size;

libavcodec/bitstream.h:768:5: 
  766. 
  767.     s->buffer= buffer;
  768.     s->size_in_bits= bit_size;
           ^
  769.     s->buffer_end= buffer + buffer_size;
  770. #ifdef ALT_BITSTREAM_READER

libavcodec/bitstream.h:769:5: 
  767.     s->buffer= buffer;
  768.     s->size_in_bits= bit_size;
  769.     s->buffer_end= buffer + buffer_size;
           ^
  770. #ifdef ALT_BITSTREAM_READER
  771.     s->index=0;

libavcodec/bitstream.h:771:5: 
  769.     s->buffer_end= buffer + buffer_size;
  770. #ifdef ALT_BITSTREAM_READER
  771.     s->index=0;
           ^
  772. #elif defined LIBMPEG2_BITSTREAM_READER
  773.     s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));

libavcodec/bitstream.h:781:1: return from a call to init_get_bits
  779.     skip_bits_long(s, 0);
  780. #endif
  781. }
       ^
  782. 
  783. static inline void align_get_bits(GetBitContext *s)

libavcodec/vp3.c:2138:9: Taking false branch
2136.     init_get_bits(&gb, buf, buf_size * 8);
2137. 
2138.     if (s->theora && get_bits1(&gb))
              ^
2139.     {
2140.         av_log(avctx, AV_LOG_ERROR, "Header packet passed to frame decoder, skipping\n");

libavcodec/vp3.c:2144:20: 
2142.     }
2143. 
2144.     s->keyframe = !get_bits1(&gb);
                         ^
2145.     if (!s->theora)
2146.         skip_bits(&gb, 1);

libavcodec/bitstream.h:686:1: start of procedure get_bits1()
  684. }
  685. 
  686. static inline unsigned int get_bits1(GetBitContext *s){
       ^
  687. #ifdef ALT_BITSTREAM_READER
  688.     int index= s->index;

libavcodec/bitstream.h:688:5: 
  686. static inline unsigned int get_bits1(GetBitContext *s){
  687. #ifdef ALT_BITSTREAM_READER
  688.     int index= s->index;
           ^
  689.     uint8_t result= s->buffer[ index>>3 ];
  690. #ifdef ALT_BITSTREAM_READER_LE

libavcodec/bitstream.h:689:5: 
  687. #ifdef ALT_BITSTREAM_READER
  688.     int index= s->index;
  689.     uint8_t result= s->buffer[ index>>3 ];
           ^
  690. #ifdef ALT_BITSTREAM_READER_LE
  691.     result>>= (index&0x07);
