libavcodec/mss2.c:483: error: Null Dereference
  pointer `&gb->buffer` last assigned on line 481 could be null and is dereferenced by call to `get_bits1()` at line 483, column 20.

libavcodec/mss2.c:461:1: start of procedure mss2_decode_frame()
459. #define ARITH2_PADDING 2
460. 
461. static int mss2_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     ^
462.                              AVPacket *avpkt)
463. {

libavcodec/mss2.c:464:5: 
462.                              AVPacket *avpkt)
463. {
464.     const uint8_t *buf = avpkt->data;
         ^
465.     int buf_size       = avpkt->size;
466.     MSS2Context *ctx = avctx->priv_data;

libavcodec/mss2.c:465:5: 
463. {
464.     const uint8_t *buf = avpkt->data;
465.     int buf_size       = avpkt->size;
         ^
466.     MSS2Context *ctx = avctx->priv_data;
467.     MSS12Context *c  = &ctx->c;

libavcodec/mss2.c:466:5: 
464.     const uint8_t *buf = avpkt->data;
465.     int buf_size       = avpkt->size;
466.     MSS2Context *ctx = avctx->priv_data;
         ^
467.     MSS12Context *c  = &ctx->c;
468.     AVFrame *frame   = data;

libavcodec/mss2.c:467:5: 
465.     int buf_size       = avpkt->size;
466.     MSS2Context *ctx = avctx->priv_data;
467.     MSS12Context *c  = &ctx->c;
         ^
468.     AVFrame *frame   = data;
469.     GetBitContext gb;

libavcodec/mss2.c:468:5: 
466.     MSS2Context *ctx = avctx->priv_data;
467.     MSS12Context *c  = &ctx->c;
468.     AVFrame *frame   = data;
         ^
469.     GetBitContext gb;
470.     GetByteContext gB;

libavcodec/mss2.c:476:5: 
474. 
475.     Rectangle wmv9rects[MAX_WMV9_RECTANGLES], *r;
476.     int used_rects = 0, i, implicit_rect = 0, av_uninit(wmv9_mask);
         ^
477. 
478.     av_assert0(FF_INPUT_BUFFER_PADDING_SIZE >=

libavcodec/mss2.c:478:5: Taking false branch
476.     int used_rects = 0, i, implicit_rect = 0, av_uninit(wmv9_mask);
477. 
478.     av_assert0(FF_INPUT_BUFFER_PADDING_SIZE >=
         ^
479.                ARITH2_PADDING + (MIN_CACHE_BITS + 7) / 8);
480. 

libavcodec/mss2.c:478:5: Loop condition is false. Leaving loop
476.     int used_rects = 0, i, implicit_rect = 0, av_uninit(wmv9_mask);
477. 
478.     av_assert0(FF_INPUT_BUFFER_PADDING_SIZE >=
         ^
479.                ARITH2_PADDING + (MIN_CACHE_BITS + 7) / 8);
480. 

libavcodec/mss2.c:481:5: 
479.                ARITH2_PADDING + (MIN_CACHE_BITS + 7) / 8);
480. 
481.     init_get_bits(&gb, buf, buf_size * 8);
         ^
482. 
483.     if (keyframe = get_bits1(&gb))

libavcodec/get_bits.h:376:1: start of procedure init_get_bits()
  374.  * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
  375.  */
  376. static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
       ^
  377.                                 int bit_size)
  378. {

libavcodec/get_bits.h:380:5: 
  378. {
  379.     int buffer_size;
  380.     int ret = 0;
           ^
  381. 
  382.     if (bit_size > INT_MAX - 7 || bit_size < 0 || !buffer) {

libavcodec/get_bits.h:382:9: Taking true branch
  380.     int ret = 0;
  381. 
  382.     if (bit_size > INT_MAX - 7 || bit_size < 0 || !buffer) {
               ^
  383.         bit_size    = 0;
  384.         buffer      = NULL;

libavcodec/get_bits.h:383:9: 
  381. 
  382.     if (bit_size > INT_MAX - 7 || bit_size < 0 || !buffer) {
  383.         bit_size    = 0;
               ^
  384.         buffer      = NULL;
  385.         ret         = AVERROR_INVALIDDATA;

libavcodec/get_bits.h:384:9: 
  382.     if (bit_size > INT_MAX - 7 || bit_size < 0 || !buffer) {
  383.         bit_size    = 0;
  384.         buffer      = NULL;
               ^
  385.         ret         = AVERROR_INVALIDDATA;
  386.     }

libavcodec/get_bits.h:385:9: 
  383.         bit_size    = 0;
  384.         buffer      = NULL;
  385.         ret         = AVERROR_INVALIDDATA;
               ^
  386.     }
  387. 

libavcodec/get_bits.h:388:5: 
  386.     }
  387. 
  388.     buffer_size = (bit_size + 7) >> 3;
           ^
  389. 
  390.     s->buffer             = buffer;

libavcodec/get_bits.h:390:5: 
  388.     buffer_size = (bit_size + 7) >> 3;
  389. 
  390.     s->buffer             = buffer;
           ^
  391.     s->size_in_bits       = bit_size;
  392. #if !UNCHECKED_BITSTREAM_READER

libavcodec/get_bits.h:391:5: 
  389. 
  390.     s->buffer             = buffer;
  391.     s->size_in_bits       = bit_size;
           ^
  392. #if !UNCHECKED_BITSTREAM_READER
  393.     s->size_in_bits_plus8 = bit_size + 8;

libavcodec/get_bits.h:393:5: 
  391.     s->size_in_bits       = bit_size;
  392. #if !UNCHECKED_BITSTREAM_READER
  393.     s->size_in_bits_plus8 = bit_size + 8;
           ^
  394. #endif
  395.     s->buffer_end         = buffer + buffer_size;

libavcodec/get_bits.h:395:5: 
  393.     s->size_in_bits_plus8 = bit_size + 8;
  394. #endif
  395.     s->buffer_end         = buffer + buffer_size;
           ^
  396.     s->index              = 0;
  397. 

libavcodec/get_bits.h:396:5: 
  394. #endif
  395.     s->buffer_end         = buffer + buffer_size;
  396.     s->index              = 0;
           ^
  397. 
  398.     return ret;

libavcodec/get_bits.h:398:5: 
  396.     s->index              = 0;
  397. 
  398.     return ret;
           ^
  399. }
  400. 

libavcodec/get_bits.h:399:1: return from a call to init_get_bits
  397. 
  398.     return ret;
  399. }
       ^
  400. 
  401. /**

libavcodec/mss2.c:483:9: 
481.     init_get_bits(&gb, buf, buf_size * 8);
482. 
483.     if (keyframe = get_bits1(&gb))
             ^
484.         skip_bits(&gb, 7);
485.     has_wmv9 = get_bits1(&gb);

libavcodec/get_bits.h:272:1: start of procedure get_bits1()
  270. }
  271. 
  272. static inline unsigned int get_bits1(GetBitContext *s)
       ^
  273. {
  274.     unsigned int index = s->index;

libavcodec/get_bits.h:274:5: 
  272. static inline unsigned int get_bits1(GetBitContext *s)
  273. {
  274.     unsigned int index = s->index;
           ^
  275.     uint8_t result     = s->buffer[index >> 3];
  276. #ifdef BITSTREAM_READER_LE

libavcodec/get_bits.h:275:5: 
  273. {
  274.     unsigned int index = s->index;
  275.     uint8_t result     = s->buffer[index >> 3];
           ^
  276. #ifdef BITSTREAM_READER_LE
  277.     result >>= index & 7;
