libavcodec/mpc8.c:200: error: Null Dereference
  pointer `gb->buffer` last assigned on line 199 could be null and is dereferenced by call to `skip_bits()` at line 200, column 5.

libavcodec/mpc8.c:181:1: start of procedure mpc8_decode_frame()
179. }
180. 
181. static int mpc8_decode_frame(AVCodecContext * avctx,
     ^
182.                             void *data, int *data_size,
183.                             const uint8_t * buf, int buf_size)

libavcodec/mpc8.c:185:5: 
183.                             const uint8_t * buf, int buf_size)
184. {
185.     MPCContext *c = avctx->priv_data;
         ^
186.     GetBitContext gb2, *gb = &gb2;
187.     int i, j, k, ch, cnt, res, t;

libavcodec/mpc8.c:186:5: 
184. {
185.     MPCContext *c = avctx->priv_data;
186.     GetBitContext gb2, *gb = &gb2;
         ^
187.     int i, j, k, ch, cnt, res, t;
188.     Band *bands = c->bands;

libavcodec/mpc8.c:188:5: 
186.     GetBitContext gb2, *gb = &gb2;
187.     int i, j, k, ch, cnt, res, t;
188.     Band *bands = c->bands;
         ^
189.     int off;
190.     int maxband, keyframe;

libavcodec/mpc8.c:193:16: Condition is false
191.     int last[2];
192. 
193.     keyframe = c->cur_frame == 0;
                    ^
194. 
195.     if(keyframe){

libavcodec/mpc8.c:193:5: 
191.     int last[2];
192. 
193.     keyframe = c->cur_frame == 0;
         ^
194. 
195.     if(keyframe){

libavcodec/mpc8.c:195:8: Taking false branch
193.     keyframe = c->cur_frame == 0;
194. 
195.     if(keyframe){
            ^
196.         memset(c->Q, 0, sizeof(c->Q));
197.         c->last_bits_used = 0;

libavcodec/mpc8.c:199:5: 
197.         c->last_bits_used = 0;
198.     }
199.     init_get_bits(gb, buf, buf_size * 8);
         ^
200.     skip_bits(gb, c->last_bits_used & 7);
201. 

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/mpc8.c:200:5: 
198.     }
199.     init_get_bits(gb, buf, buf_size * 8);
200.     skip_bits(gb, c->last_bits_used & 7);
         ^
201. 
202.     if(keyframe)

libavcodec/bitstream.h:657:1: start of procedure skip_bits()
  655. }
  656. 
  657. static inline void skip_bits(GetBitContext *s, int n){
       ^
  658.  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
  659.     OPEN_READER(re, s)

libavcodec/bitstream.h:659:5: 
  657. static inline void skip_bits(GetBitContext *s, int n){
  658.  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
  659.     OPEN_READER(re, s)
           ^
  660.     UPDATE_CACHE(re, s)
  661.     LAST_SKIP_BITS(re, s, n)

libavcodec/bitstream.h:660:5: 
  658.  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
  659.     OPEN_READER(re, s)
  660.     UPDATE_CACHE(re, s)
           ^
  661.     LAST_SKIP_BITS(re, s, n)
  662.     CLOSE_READER(re, s)
