libavcodec/mpegvideo.c:1129: error: Null Dereference
  pointer `s->mb_index2xy` last assigned on line 1123 could be null and is dereferenced at line 1129, column 5.

libavcodec/mpegvideo.c:1095:1: start of procedure init_context_frame()
1093.  * Initialize and allocates MpegEncContext fields dependent on the resolution.
1094.  */
1095. static int init_context_frame(MpegEncContext *s)
      ^
1096. {
1097.     int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;

libavcodec/mpegvideo.c:1099:5: 
1097.     int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;
1098. 
1099.     s->mb_width   = (s->width + 15) / 16;
          ^
1100.     s->mb_stride  = s->mb_width + 1;
1101.     s->b8_stride  = s->mb_width * 2 + 1;

libavcodec/mpegvideo.c:1100:5: 
1098. 
1099.     s->mb_width   = (s->width + 15) / 16;
1100.     s->mb_stride  = s->mb_width + 1;
          ^
1101.     s->b8_stride  = s->mb_width * 2 + 1;
1102.     mb_array_size = s->mb_height * s->mb_stride;

libavcodec/mpegvideo.c:1101:5: 
1099.     s->mb_width   = (s->width + 15) / 16;
1100.     s->mb_stride  = s->mb_width + 1;
1101.     s->b8_stride  = s->mb_width * 2 + 1;
          ^
1102.     mb_array_size = s->mb_height * s->mb_stride;
1103.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;

libavcodec/mpegvideo.c:1102:5: 
1100.     s->mb_stride  = s->mb_width + 1;
1101.     s->b8_stride  = s->mb_width * 2 + 1;
1102.     mb_array_size = s->mb_height * s->mb_stride;
          ^
1103.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;
1104. 

libavcodec/mpegvideo.c:1103:5: 
1101.     s->b8_stride  = s->mb_width * 2 + 1;
1102.     mb_array_size = s->mb_height * s->mb_stride;
1103.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;
          ^
1104. 
1105.     /* set default edge pos, will be overriden

libavcodec/mpegvideo.c:1107:5: 
1105.     /* set default edge pos, will be overriden
1106.      * in decode_header if needed */
1107.     s->h_edge_pos = s->mb_width * 16;
          ^
1108.     s->v_edge_pos = s->mb_height * 16;
1109. 

libavcodec/mpegvideo.c:1108:5: 
1106.      * in decode_header if needed */
1107.     s->h_edge_pos = s->mb_width * 16;
1108.     s->v_edge_pos = s->mb_height * 16;
          ^
1109. 
1110.     s->mb_num     = s->mb_width * s->mb_height;

libavcodec/mpegvideo.c:1110:5: 
1108.     s->v_edge_pos = s->mb_height * 16;
1109. 
1110.     s->mb_num     = s->mb_width * s->mb_height;
          ^
1111. 
1112.     s->block_wrap[0] =

libavcodec/mpegvideo.c:1112:5: 
1110.     s->mb_num     = s->mb_width * s->mb_height;
1111. 
1112.     s->block_wrap[0] =
          ^
1113.     s->block_wrap[1] =
1114.     s->block_wrap[2] =

libavcodec/mpegvideo.c:1116:5: 
1114.     s->block_wrap[2] =
1115.     s->block_wrap[3] = s->b8_stride;
1116.     s->block_wrap[4] =
          ^
1117.     s->block_wrap[5] = s->mb_stride;
1118. 

libavcodec/mpegvideo.c:1119:5: 
1117.     s->block_wrap[5] = s->mb_stride;
1118. 
1119.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
          ^
1120.     c_size  = s->mb_stride * (s->mb_height + 1);
1121.     yc_size = y_size + 2   * c_size;

libavcodec/mpegvideo.c:1120:5: 
1118. 
1119.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
1120.     c_size  = s->mb_stride * (s->mb_height + 1);
          ^
1121.     yc_size = y_size + 2   * c_size;
1122. 

libavcodec/mpegvideo.c:1121:5: 
1119.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
1120.     c_size  = s->mb_stride * (s->mb_height + 1);
1121.     yc_size = y_size + 2   * c_size;
          ^
1122. 
1123.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),

libavcodec/mpegvideo.c:1123:5: 
1121.     yc_size = y_size + 2   * c_size;
1122. 
1123.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
          ^
1124.                       fail); // error ressilience code looks cleaner with this
1125.     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:1123:5: Taking true branch
1121.     yc_size = y_size + 2   * c_size;
1122. 
1123.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
          ^
1124.                       fail); // error ressilience code looks cleaner with this
1125.     for (y = 0; y < s->mb_height; y++)

libavcodec/mpegvideo.c:1123:5: Taking false branch
1121.     yc_size = y_size + 2   * c_size;
1122. 
1123.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
          ^
1124.                       fail); // error ressilience code looks cleaner with this
1125.     for (y = 0; y < s->mb_height; y++)

libavcodec/mpegvideo.c:1125:10: 
1123.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
1124.                       fail); // error ressilience code looks cleaner with this
1125.     for (y = 0; y < s->mb_height; y++)
               ^
1126.         for (x = 0; x < s->mb_width; x++)
1127.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;

libavcodec/mpegvideo.c:1125:17: Loop condition is false. Leaving loop
1123.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
1124.                       fail); // error ressilience code looks cleaner with this
1125.     for (y = 0; y < s->mb_height; y++)
                      ^
1126.         for (x = 0; x < s->mb_width; x++)
1127.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;

libavcodec/mpegvideo.c:1129:5: 
1127.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;
1128. 
1129.     s->mb_index2xy[s->mb_height * s->mb_width] =
          ^
1130.         (s->mb_height - 1) * s->mb_stride + s->mb_width; // FIXME really needed?
1131. 
