libavcodec/mpegvideo.c:887: error: Null Dereference
  pointer `s->mb_index2xy` last assigned on line 881 could be null and is dereferenced at line 887, column 5.

libavcodec/mpegvideo.c:852:1: start of procedure init_context_frame()
850.  * Initialize and allocates MpegEncContext fields dependent on the resolution.
851.  */
852. static int init_context_frame(MpegEncContext *s)
     ^
853. {
854.     int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;

libavcodec/mpegvideo.c:856:5: 
854.     int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;
855. 
856.     s->mb_width   = (s->width + 15) / 16;
         ^
857.     s->mb_stride  = s->mb_width + 1;
858.     s->b8_stride  = s->mb_width * 2 + 1;

libavcodec/mpegvideo.c:857:5: 
855. 
856.     s->mb_width   = (s->width + 15) / 16;
857.     s->mb_stride  = s->mb_width + 1;
         ^
858.     s->b8_stride  = s->mb_width * 2 + 1;
859.     s->b4_stride  = s->mb_width * 4 + 1;

libavcodec/mpegvideo.c:858:5: 
856.     s->mb_width   = (s->width + 15) / 16;
857.     s->mb_stride  = s->mb_width + 1;
858.     s->b8_stride  = s->mb_width * 2 + 1;
         ^
859.     s->b4_stride  = s->mb_width * 4 + 1;
860.     mb_array_size = s->mb_height * s->mb_stride;

libavcodec/mpegvideo.c:859:5: 
857.     s->mb_stride  = s->mb_width + 1;
858.     s->b8_stride  = s->mb_width * 2 + 1;
859.     s->b4_stride  = s->mb_width * 4 + 1;
         ^
860.     mb_array_size = s->mb_height * s->mb_stride;
861.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;

libavcodec/mpegvideo.c:860:5: 
858.     s->b8_stride  = s->mb_width * 2 + 1;
859.     s->b4_stride  = s->mb_width * 4 + 1;
860.     mb_array_size = s->mb_height * s->mb_stride;
         ^
861.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;
862. 

libavcodec/mpegvideo.c:861:5: 
859.     s->b4_stride  = s->mb_width * 4 + 1;
860.     mb_array_size = s->mb_height * s->mb_stride;
861.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;
         ^
862. 
863.     /* set default edge pos, will be overriden

libavcodec/mpegvideo.c:865:5: 
863.     /* set default edge pos, will be overriden
864.      * in decode_header if needed */
865.     s->h_edge_pos = s->mb_width * 16;
         ^
866.     s->v_edge_pos = s->mb_height * 16;
867. 

libavcodec/mpegvideo.c:866:5: 
864.      * in decode_header if needed */
865.     s->h_edge_pos = s->mb_width * 16;
866.     s->v_edge_pos = s->mb_height * 16;
         ^
867. 
868.     s->mb_num     = s->mb_width * s->mb_height;

libavcodec/mpegvideo.c:868:5: 
866.     s->v_edge_pos = s->mb_height * 16;
867. 
868.     s->mb_num     = s->mb_width * s->mb_height;
         ^
869. 
870.     s->block_wrap[0] =

libavcodec/mpegvideo.c:870:5: 
868.     s->mb_num     = s->mb_width * s->mb_height;
869. 
870.     s->block_wrap[0] =
         ^
871.     s->block_wrap[1] =
872.     s->block_wrap[2] =

libavcodec/mpegvideo.c:874:5: 
872.     s->block_wrap[2] =
873.     s->block_wrap[3] = s->b8_stride;
874.     s->block_wrap[4] =
         ^
875.     s->block_wrap[5] = s->mb_stride;
876. 

libavcodec/mpegvideo.c:877:5: 
875.     s->block_wrap[5] = s->mb_stride;
876. 
877.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
         ^
878.     c_size  = s->mb_stride * (s->mb_height + 1);
879.     yc_size = y_size + 2   * c_size;

libavcodec/mpegvideo.c:878:5: 
876. 
877.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
878.     c_size  = s->mb_stride * (s->mb_height + 1);
         ^
879.     yc_size = y_size + 2   * c_size;
880. 

libavcodec/mpegvideo.c:879:5: 
877.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
878.     c_size  = s->mb_stride * (s->mb_height + 1);
879.     yc_size = y_size + 2   * c_size;
         ^
880. 
881.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),

libavcodec/mpegvideo.c:881:5: 
879.     yc_size = y_size + 2   * c_size;
880. 
881.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
         ^
882.                       fail); // error ressilience code looks cleaner with this
883.     for (y = 0; y < s->mb_height; y++)

libavutil/mem.c:205:1: start of procedure av_mallocz()
  203. }
  204. 
  205. void *av_mallocz(size_t size)
       ^
  206. {
  207.     void *ptr = av_malloc(size);

libavutil/mem.c:207:5: 
  205. void *av_mallocz(size_t size)
  206. {
  207.     void *ptr = av_malloc(size);
           ^
  208.     if (ptr)
  209.         memset(ptr, 0, size);

libavutil/mem.c:62:1: start of procedure av_malloc()
    60.  * linker will do it automatically. */
    61. 
    62. void *av_malloc(size_t size)
        ^
    63. {
    64.     void *ptr = NULL;

libavutil/mem.c:64:5: 
    62. void *av_malloc(size_t size)
    63. {
    64.     void *ptr = NULL;
            ^
    65. #if CONFIG_MEMALIGN_HACK
    66.     long diff;

libavutil/mem.c:70:9: Taking true branch
    68. 
    69.     /* let's disallow possibly ambiguous cases */
    70.     if (size > (INT_MAX - 32) || !size)
                ^
    71.         return NULL;
    72. 

libavutil/mem.c:71:9: 
    69.     /* let's disallow possibly ambiguous cases */
    70.     if (size > (INT_MAX - 32) || !size)
    71.         return NULL;
                ^
    72. 
    73. #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)

libavutil/mem.c:208:9: Taking false branch
  206. {
  207.     void *ptr = av_malloc(size);
  208.     if (ptr)
               ^
  209.         memset(ptr, 0, size);
  210.     return ptr;

libavutil/mem.c:210:5: 
  208.     if (ptr)
  209.         memset(ptr, 0, size);
  210.     return ptr;
           ^
  211. }
  212. 

libavutil/mem.c:211:1: return from a call to av_mallocz
  209.         memset(ptr, 0, size);
  210.     return ptr;
  211. }
       ^
  212. 
  213. char *av_strdup(const char *s)

libavcodec/mpegvideo.c:881:5: Taking true branch
879.     yc_size = y_size + 2   * c_size;
880. 
881.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
         ^
882.                       fail); // error ressilience code looks cleaner with this
883.     for (y = 0; y < s->mb_height; y++)

libavcodec/mpegvideo.c:881:5: Taking false branch
879.     yc_size = y_size + 2   * c_size;
880. 
881.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
         ^
882.                       fail); // error ressilience code looks cleaner with this
883.     for (y = 0; y < s->mb_height; y++)

libavcodec/mpegvideo.c:883:10: 
881.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
882.                       fail); // error ressilience code looks cleaner with this
883.     for (y = 0; y < s->mb_height; y++)
              ^
884.         for (x = 0; x < s->mb_width; x++)
885.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;

libavcodec/mpegvideo.c:883:17: Loop condition is false. Leaving loop
881.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
882.                       fail); // error ressilience code looks cleaner with this
883.     for (y = 0; y < s->mb_height; y++)
                     ^
884.         for (x = 0; x < s->mb_width; x++)
885.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;

libavcodec/mpegvideo.c:887:5: 
885.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;
886. 
887.     s->mb_index2xy[s->mb_height * s->mb_width] =
         ^
888.         (s->mb_height - 1) * s->mb_stride + s->mb_width; // FIXME really needed?
889. 
