libavformat/oggdec.c:192: error: Null Dereference
  pointer `nb` last assigned on line 189 could be null and is dereferenced by call to `memcpy()` at line 192, column 9.

libavformat/oggdec.c:186:1: start of procedure ogg_new_buf()
184. }
185. 
186. static int ogg_new_buf(struct ogg *ogg, int idx)
     ^
187. {
188.     struct ogg_stream *os = ogg->streams + idx;

libavformat/oggdec.c:188:5: 
186. static int ogg_new_buf(struct ogg *ogg, int idx)
187. {
188.     struct ogg_stream *os = ogg->streams + idx;
         ^
189.     uint8_t *nb = av_malloc(os->bufsize);
190.     int size = os->bufpos - os->pstart;

libavformat/oggdec.c:189:5: 
187. {
188.     struct ogg_stream *os = ogg->streams + idx;
189.     uint8_t *nb = av_malloc(os->bufsize);
         ^
190.     int size = os->bufpos - os->pstart;
191.     if(os->buf){

libavutil/mem.c:64:1: start of procedure av_malloc()
  62.    linker will do it automatically. */
  63. 
  64. void *av_malloc(size_t size)
      ^
  65. {
  66.     void *ptr = NULL;

libavutil/mem.c:66:5: 
  64. void *av_malloc(size_t size)
  65. {
  66.     void *ptr = NULL;
          ^
  67. #if CONFIG_MEMALIGN_HACK
  68.     long diff;

libavutil/mem.c:72:8: Taking true branch
  70. 
  71.     /* let's disallow possible ambiguous cases */
  72.     if(size > (INT_MAX-32) )
             ^
  73.         return NULL;
  74. 

libavutil/mem.c:73:9: 
  71.     /* let's disallow possible ambiguous cases */
  72.     if(size > (INT_MAX-32) )
  73.         return NULL;
              ^
  74. 
  75. #if CONFIG_MEMALIGN_HACK

libavutil/mem.c:115:1: return from a call to av_malloc
  113. #endif
  114.     return ptr;
  115. }
       ^
  116. 
  117. void *av_realloc(void *ptr, size_t size)

libavformat/oggdec.c:190:5: 
188.     struct ogg_stream *os = ogg->streams + idx;
189.     uint8_t *nb = av_malloc(os->bufsize);
190.     int size = os->bufpos - os->pstart;
         ^
191.     if(os->buf){
192.         memcpy(nb, os->buf + os->pstart, size);

libavformat/oggdec.c:191:8: Taking true branch
189.     uint8_t *nb = av_malloc(os->bufsize);
190.     int size = os->bufpos - os->pstart;
191.     if(os->buf){
            ^
192.         memcpy(nb, os->buf + os->pstart, size);
193.         av_free(os->buf);

libavformat/oggdec.c:192:9: 
190.     int size = os->bufpos - os->pstart;
191.     if(os->buf){
192.         memcpy(nb, os->buf + os->pstart, size);
             ^
193.         av_free(os->buf);
194.     }

static int ogg_new_buf(struct ogg *ogg, int idx)
{
    struct ogg_stream *os = ogg->streams + idx;
    uint8_t *nb = av_malloc(os->bufsize);
    int size = os->bufpos - os->pstart;
    if(os->buf){
        memcpy(nb, os->buf + os->pstart, size);
        av_free(os->buf);
    }
    os->buf = nb;
    os->bufpos = size;
    os->pstart = 0;
    return 0;
}
['static int ogg_new_buf(struct ogg *ogg, int idx)\n{\n    struct ogg_stream *os = ogg->streams + idx;\n    uint8_t *nb = av_malloc(os->bufsize);\n    int size = os->bufpos - os->pstart;\n    if(os->buf){\n        memcpy(nb, os->buf + os->pstart, size);\n        av_free(os->buf);\n    }\n    os->buf = nb;\n    os->bufpos = size;\n    os->pstart = 0;\n    return 0;\n}', 'void *av_malloc(size_t size)\n{\n    void *ptr = NULL;\n#if CONFIG_MEMALIGN_HACK\n    long diff;\n#endif\n    if(size > (INT_MAX-32) )\n        return NULL;\n#if CONFIG_MEMALIGN_HACK\n    ptr = malloc(size+32);\n    if(!ptr)\n        return ptr;\n    diff= ((-(long)ptr - 1)&31) + 1;\n    ptr = (char*)ptr + diff;\n    ((char*)ptr)[-1]= diff;\n#elif HAVE_POSIX_MEMALIGN\n    if (posix_memalign(&ptr,32,size))\n        ptr = NULL;\n#elif HAVE_MEMALIGN\n    ptr = memalign(32,size);\n#else\n    ptr = malloc(size);\n#endif\n    return ptr;\n}']