libavcodec/vp3.c:1920: error: Null Dereference
  pointer `&gb->buffer` last assigned on line 1918 could be null and is dereferenced by call to `get_bits1()` at line 1920, column 22.

libavcodec/vp3.c:1908:1: start of procedure vp3_decode_frame()
1906. }
1907. 
1908. static int vp3_decode_frame(AVCodecContext *avctx,
      ^
1909.                             void *data, int *data_size,
1910.                             AVPacket *avpkt)

libavcodec/vp3.c:1912:5: 
1910.                             AVPacket *avpkt)
1911. {
1912.     const uint8_t *buf = avpkt->data;
          ^
1913.     int buf_size = avpkt->size;
1914.     Vp3DecodeContext *s = avctx->priv_data;

libavcodec/vp3.c:1913:5: 
1911. {
1912.     const uint8_t *buf = avpkt->data;
1913.     int buf_size = avpkt->size;
          ^
1914.     Vp3DecodeContext *s = avctx->priv_data;
1915.     GetBitContext gb;

libavcodec/vp3.c:1914:5: 
1912.     const uint8_t *buf = avpkt->data;
1913.     int buf_size = avpkt->size;
1914.     Vp3DecodeContext *s = avctx->priv_data;
          ^
1915.     GetBitContext gb;
1916.     int i;

libavcodec/vp3.c:1918:5: 
1916.     int i;
1917. 
1918.     init_get_bits(&gb, buf, buf_size * 8);
          ^
1919. 
1920.     if (s->theora && get_bits1(&gb))

libavcodec/get_bits.h:339:1: start of procedure init_get_bits()
  337.  * @param bit_size the size of the buffer in bits
  338.  */
  339. static inline void init_get_bits(GetBitContext *s, const uint8_t *buffer,
       ^
  340.                                  int bit_size)
  341. {

libavcodec/get_bits.h:342:5: 
  340.                                  int bit_size)
  341. {
  342.     int buffer_size = (bit_size+7)>>3;
           ^
  343.     if (buffer_size < 0 || bit_size < 0) {
  344.         buffer_size = bit_size = 0;

libavcodec/get_bits.h:343:9: Taking true branch
  341. {
  342.     int buffer_size = (bit_size+7)>>3;
  343.     if (buffer_size < 0 || bit_size < 0) {
               ^
  344.         buffer_size = bit_size = 0;
  345.         buffer = NULL;

libavcodec/get_bits.h:344:9: 
  342.     int buffer_size = (bit_size+7)>>3;
  343.     if (buffer_size < 0 || bit_size < 0) {
  344.         buffer_size = bit_size = 0;
               ^
  345.         buffer = NULL;
  346.     }

libavcodec/get_bits.h:345:9: 
  343.     if (buffer_size < 0 || bit_size < 0) {
  344.         buffer_size = bit_size = 0;
  345.         buffer = NULL;
               ^
  346.     }
  347. 

libavcodec/get_bits.h:348:5: 
  346.     }
  347. 
  348.     s->buffer       = buffer;
           ^
  349.     s->size_in_bits = bit_size;
  350. #if !UNCHECKED_BITSTREAM_READER

libavcodec/get_bits.h:349:5: 
  347. 
  348.     s->buffer       = buffer;
  349.     s->size_in_bits = bit_size;
           ^
  350. #if !UNCHECKED_BITSTREAM_READER
  351.     s->size_in_bits_plus8 = bit_size + 8;

libavcodec/get_bits.h:351:5: 
  349.     s->size_in_bits = bit_size;
  350. #if !UNCHECKED_BITSTREAM_READER
  351.     s->size_in_bits_plus8 = bit_size + 8;
           ^
  352. #endif
  353.     s->buffer_end   = buffer + buffer_size;

libavcodec/get_bits.h:353:5: 
  351.     s->size_in_bits_plus8 = bit_size + 8;
  352. #endif
  353.     s->buffer_end   = buffer + buffer_size;
           ^
  354.     s->index        = 0;
  355. }

libavcodec/get_bits.h:354:5: 
  352. #endif
  353.     s->buffer_end   = buffer + buffer_size;
  354.     s->index        = 0;
           ^
  355. }
  356. 

libavcodec/get_bits.h:355:1: return from a call to init_get_bits
  353.     s->buffer_end   = buffer + buffer_size;
  354.     s->index        = 0;
  355. }
       ^
  356. 
  357. static inline void align_get_bits(GetBitContext *s)

libavcodec/vp3.c:1920:9: Taking true branch
1918.     init_get_bits(&gb, buf, buf_size * 8);
1919. 
1920.     if (s->theora && get_bits1(&gb))
              ^
1921.     {
1922.         av_log(avctx, AV_LOG_ERROR, "Header packet passed to frame decoder, skipping\n");

libavcodec/vp3.c:1920:22: 
1918.     init_get_bits(&gb, buf, buf_size * 8);
1919. 
1920.     if (s->theora && get_bits1(&gb))
                           ^
1921.     {
1922.         av_log(avctx, AV_LOG_ERROR, "Header packet passed to frame decoder, skipping\n");

libavcodec/get_bits.h:255:1: start of procedure get_bits1()
  253. }
  254. 
  255. static inline unsigned int get_bits1(GetBitContext *s)
       ^
  256. {
  257.     unsigned int index = s->index;

libavcodec/get_bits.h:257:5: 
  255. static inline unsigned int get_bits1(GetBitContext *s)
  256. {
  257.     unsigned int index = s->index;
           ^
  258.     uint8_t result = s->buffer[index>>3];
  259. #ifdef BITSTREAM_READER_LE

libavcodec/get_bits.h:258:5: 
  256. {
  257.     unsigned int index = s->index;
  258.     uint8_t result = s->buffer[index>>3];
           ^
  259. #ifdef BITSTREAM_READER_LE
  260.     result >>= index & 7;
