libavformat/oggparsevorbis.c:138: error: Null Dereference
  pointer `ptr` last assigned on line 136 could be null and is dereferenced at line 138, column 5.

libavformat/oggparsevorbis.c:128:1: start of procedure fixup_vorbis_headers()
126. 
127. 
128. static unsigned int
     ^
129. fixup_vorbis_headers(AVFormatContext * as, struct oggvorbis_private *priv,
130.                      uint8_t **buf)

libavformat/oggparsevorbis.c:135:5: 
133.     unsigned char *ptr;
134. 
135.     len = priv->len[0] + priv->len[1] + priv->len[2];
         ^
136.     ptr = *buf = av_mallocz(len + len/255 + 64);
137. 

libavformat/oggparsevorbis.c:136:5: 
134. 
135.     len = priv->len[0] + priv->len[1] + priv->len[2];
136.     ptr = *buf = av_mallocz(len + len/255 + 64);
         ^
137. 
138.     ptr[0] = 2;

libavutil/mem.c:139:1: start of procedure av_mallocz()
  137. }
  138. 
  139. void *av_mallocz(unsigned int size)
       ^
  140. {
  141.     void *ptr = av_malloc(size);

libavutil/mem.c:141:5: 
  139. void *av_mallocz(unsigned int size)
  140. {
  141.     void *ptr = av_malloc(size);
           ^
  142.     if (ptr)
  143.         memset(ptr, 0, size);

libavutil/mem.c:47:1: start of procedure av_malloc()
    45.    linker will do it automatically. */
    46. 
    47. void *av_malloc(unsigned int size)
        ^
    48. {
    49.     void *ptr = NULL;

libavutil/mem.c:49:5: 
    47. void *av_malloc(unsigned int size)
    48. {
    49.     void *ptr = NULL;
            ^
    50. #if CONFIG_MEMALIGN_HACK
    51.     long diff;

libavutil/mem.c:55:8: Taking true branch
    53. 
    54.     /* let's disallow possible ambiguous cases */
    55.     if(size > (INT_MAX-16) )
               ^
    56.         return NULL;
    57. 

libavutil/mem.c:56:9: 
    54.     /* let's disallow possible ambiguous cases */
    55.     if(size > (INT_MAX-16) )
    56.         return NULL;
                ^
    57. 
    58. #if CONFIG_MEMALIGN_HACK

libavutil/mem.c:99:1: return from a call to av_malloc
     97. #endif
     98.     return ptr;
     99. }
         ^
    100. 
    101. void *av_realloc(void *ptr, unsigned int size)

libavutil/mem.c:142:9: Taking false branch
  140. {
  141.     void *ptr = av_malloc(size);
  142.     if (ptr)
               ^
  143.         memset(ptr, 0, size);
  144.     return ptr;

libavutil/mem.c:144:5: 
  142.     if (ptr)
  143.         memset(ptr, 0, size);
  144.     return ptr;
           ^
  145. }
  146. 

libavutil/mem.c:145:1: return from a call to av_mallocz
  143.         memset(ptr, 0, size);
  144.     return ptr;
  145. }
       ^
  146. 
  147. char *av_strdup(const char *s)

libavformat/oggparsevorbis.c:138:5: 
136.     ptr = *buf = av_mallocz(len + len/255 + 64);
137. 
138.     ptr[0] = 2;
         ^
139.     offset = 1;
140.     offset += av_xiphlacing(&ptr[offset], priv->len[0]);
