libavcodec/vp3.c:1861: error: Null Dereference
  pointer `&gb->buffer` last assigned on line 1853 could be null and is dereferenced by call to `get_bits1()` at line 1861, column 20.

libavcodec/vp3.c:1843:1: start of procedure vp3_decode_frame()
1841. }
1842. 
1843. static int vp3_decode_frame(AVCodecContext *avctx,
      ^
1844.                             void *data, int *data_size,
1845.                             AVPacket *avpkt)

libavcodec/vp3.c:1847:5: 
1845.                             AVPacket *avpkt)
1846. {
1847.     const uint8_t *buf = avpkt->data;
          ^
1848.     int buf_size = avpkt->size;
1849.     Vp3DecodeContext *s = avctx->priv_data;

libavcodec/vp3.c:1848:5: 
1846. {
1847.     const uint8_t *buf = avpkt->data;
1848.     int buf_size = avpkt->size;
          ^
1849.     Vp3DecodeContext *s = avctx->priv_data;
1850.     GetBitContext gb;

libavcodec/vp3.c:1849:5: 
1847.     const uint8_t *buf = avpkt->data;
1848.     int buf_size = avpkt->size;
1849.     Vp3DecodeContext *s = avctx->priv_data;
          ^
1850.     GetBitContext gb;
1851.     int i;

libavcodec/vp3.c:1853:5: 
1851.     int i;
1852. 
1853.     init_get_bits(&gb, buf, buf_size * 8);
          ^
1854. 
1855.     if (s->theora && get_bits1(&gb))

libavcodec/get_bits.h:383:1: start of procedure init_get_bits()
  381.  * responsible for checking for the buffer end yourself (take advantage of the padding)!
  382.  */
  383. static inline void init_get_bits(GetBitContext *s,
       ^
  384.                    const uint8_t *buffer, int bit_size)
  385. {

libavcodec/get_bits.h:386:5: 
  384.                    const uint8_t *buffer, int bit_size)
  385. {
  386.     int buffer_size = (bit_size+7)>>3;
           ^
  387.     if (buffer_size < 0 || bit_size < 0) {
  388.         buffer_size = bit_size = 0;

libavcodec/get_bits.h:387:9: Taking true branch
  385. {
  386.     int buffer_size = (bit_size+7)>>3;
  387.     if (buffer_size < 0 || bit_size < 0) {
               ^
  388.         buffer_size = bit_size = 0;
  389.         buffer = NULL;

libavcodec/get_bits.h:388:9: 
  386.     int buffer_size = (bit_size+7)>>3;
  387.     if (buffer_size < 0 || bit_size < 0) {
  388.         buffer_size = bit_size = 0;
               ^
  389.         buffer = NULL;
  390.     }

libavcodec/get_bits.h:389:9: 
  387.     if (buffer_size < 0 || bit_size < 0) {
  388.         buffer_size = bit_size = 0;
  389.         buffer = NULL;
               ^
  390.     }
  391. 

libavcodec/get_bits.h:392:5: 
  390.     }
  391. 
  392.     s->buffer       = buffer;
           ^
  393.     s->size_in_bits = bit_size;
  394.     s->buffer_end   = buffer + buffer_size;

libavcodec/get_bits.h:393:5: 
  391. 
  392.     s->buffer       = buffer;
  393.     s->size_in_bits = bit_size;
           ^
  394.     s->buffer_end   = buffer + buffer_size;
  395. #ifdef ALT_BITSTREAM_READER

libavcodec/get_bits.h:394:5: 
  392.     s->buffer       = buffer;
  393.     s->size_in_bits = bit_size;
  394.     s->buffer_end   = buffer + buffer_size;
           ^
  395. #ifdef ALT_BITSTREAM_READER
  396.     s->index        = 0;

libavcodec/get_bits.h:396:5: 
  394.     s->buffer_end   = buffer + buffer_size;
  395. #ifdef ALT_BITSTREAM_READER
  396.     s->index        = 0;
           ^
  397. #elif defined A32_BITSTREAM_READER
  398.     s->buffer_ptr   = (uint32_t*)((intptr_t)buffer & ~3);

libavcodec/get_bits.h:402:1: return from a call to init_get_bits
  400.     skip_bits_long(s, 0);
  401. #endif
  402. }
       ^
  403. 
  404. static inline void align_get_bits(GetBitContext *s)

libavcodec/vp3.c:1855:9: Taking false branch
1853.     init_get_bits(&gb, buf, buf_size * 8);
1854. 
1855.     if (s->theora && get_bits1(&gb))
              ^
1856.     {
1857.         av_log(avctx, AV_LOG_ERROR, "Header packet passed to frame decoder, skipping\n");

libavcodec/vp3.c:1861:20: 
1859.     }
1860. 
1861.     s->keyframe = !get_bits1(&gb);
                         ^
1862.     if (!s->theora)
1863.         skip_bits(&gb, 1);

libavcodec/get_bits.h:303:1: start of procedure get_bits1()
  301. }
  302. 
  303. static inline unsigned int get_bits1(GetBitContext *s){
       ^
  304. #ifdef ALT_BITSTREAM_READER
  305.     unsigned int index = s->index;

libavcodec/get_bits.h:305:5: 
  303. static inline unsigned int get_bits1(GetBitContext *s){
  304. #ifdef ALT_BITSTREAM_READER
  305.     unsigned int index = s->index;
           ^
  306.     uint8_t result = s->buffer[index>>3];
  307. #ifdef ALT_BITSTREAM_READER_LE

libavcodec/get_bits.h:306:5: 
  304. #ifdef ALT_BITSTREAM_READER
  305.     unsigned int index = s->index;
  306.     uint8_t result = s->buffer[index>>3];
           ^
  307. #ifdef ALT_BITSTREAM_READER_LE
  308.     result >>= index & 7;
