libavcodec/mpegvideo.c:881: error: Null Dereference
  pointer `s->mb_index2xy` last assigned on line 875 could be null and is dereferenced at line 881, column 5.

libavcodec/mpegvideo.c:846:1: start of procedure init_context_frame()
844.  * Initialize and allocates MpegEncContext fields dependent on the resolution.
845.  */
846. static int init_context_frame(MpegEncContext *s)
     ^
847. {
848.     int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;

libavcodec/mpegvideo.c:850:5: 
848.     int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;
849. 
850.     s->mb_width   = (s->width + 15) / 16;
         ^
851.     s->mb_stride  = s->mb_width + 1;
852.     s->b8_stride  = s->mb_width * 2 + 1;

libavcodec/mpegvideo.c:851:5: 
849. 
850.     s->mb_width   = (s->width + 15) / 16;
851.     s->mb_stride  = s->mb_width + 1;
         ^
852.     s->b8_stride  = s->mb_width * 2 + 1;
853.     s->b4_stride  = s->mb_width * 4 + 1;

libavcodec/mpegvideo.c:852:5: 
850.     s->mb_width   = (s->width + 15) / 16;
851.     s->mb_stride  = s->mb_width + 1;
852.     s->b8_stride  = s->mb_width * 2 + 1;
         ^
853.     s->b4_stride  = s->mb_width * 4 + 1;
854.     mb_array_size = s->mb_height * s->mb_stride;

libavcodec/mpegvideo.c:853:5: 
851.     s->mb_stride  = s->mb_width + 1;
852.     s->b8_stride  = s->mb_width * 2 + 1;
853.     s->b4_stride  = s->mb_width * 4 + 1;
         ^
854.     mb_array_size = s->mb_height * s->mb_stride;
855.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;

libavcodec/mpegvideo.c:854:5: 
852.     s->b8_stride  = s->mb_width * 2 + 1;
853.     s->b4_stride  = s->mb_width * 4 + 1;
854.     mb_array_size = s->mb_height * s->mb_stride;
         ^
855.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;
856. 

libavcodec/mpegvideo.c:855:5: 
853.     s->b4_stride  = s->mb_width * 4 + 1;
854.     mb_array_size = s->mb_height * s->mb_stride;
855.     mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;
         ^
856. 
857.     /* set default edge pos, will be overriden

libavcodec/mpegvideo.c:859:5: 
857.     /* set default edge pos, will be overriden
858.      * in decode_header if needed */
859.     s->h_edge_pos = s->mb_width * 16;
         ^
860.     s->v_edge_pos = s->mb_height * 16;
861. 

libavcodec/mpegvideo.c:860:5: 
858.      * in decode_header if needed */
859.     s->h_edge_pos = s->mb_width * 16;
860.     s->v_edge_pos = s->mb_height * 16;
         ^
861. 
862.     s->mb_num     = s->mb_width * s->mb_height;

libavcodec/mpegvideo.c:862:5: 
860.     s->v_edge_pos = s->mb_height * 16;
861. 
862.     s->mb_num     = s->mb_width * s->mb_height;
         ^
863. 
864.     s->block_wrap[0] =

libavcodec/mpegvideo.c:864:5: 
862.     s->mb_num     = s->mb_width * s->mb_height;
863. 
864.     s->block_wrap[0] =
         ^
865.     s->block_wrap[1] =
866.     s->block_wrap[2] =

libavcodec/mpegvideo.c:868:5: 
866.     s->block_wrap[2] =
867.     s->block_wrap[3] = s->b8_stride;
868.     s->block_wrap[4] =
         ^
869.     s->block_wrap[5] = s->mb_stride;
870. 

libavcodec/mpegvideo.c:871:5: 
869.     s->block_wrap[5] = s->mb_stride;
870. 
871.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
         ^
872.     c_size  = s->mb_stride * (s->mb_height + 1);
873.     yc_size = y_size + 2   * c_size;

libavcodec/mpegvideo.c:872:5: 
870. 
871.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
872.     c_size  = s->mb_stride * (s->mb_height + 1);
         ^
873.     yc_size = y_size + 2   * c_size;
874. 

libavcodec/mpegvideo.c:873:5: 
871.     y_size  = s->b8_stride * (2 * s->mb_height + 1);
872.     c_size  = s->mb_stride * (s->mb_height + 1);
873.     yc_size = y_size + 2   * c_size;
         ^
874. 
875.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),

libavcodec/mpegvideo.c:875:5: 
873.     yc_size = y_size + 2   * c_size;
874. 
875.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
         ^
876.                       fail); // error ressilience code looks cleaner with this
877.     for (y = 0; y < s->mb_height; y++)

libavutil/mem.c:158:1: start of procedure av_mallocz()
  156. }
  157. 
  158. void *av_mallocz(size_t size)
       ^
  159. {
  160.     void *ptr = av_malloc(size);

libavutil/mem.c:160:5: 
  158. void *av_mallocz(size_t size)
  159. {
  160.     void *ptr = av_malloc(size);
           ^
  161.     if (ptr)
  162.         memset(ptr, 0, size);

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

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

libavutil/mem.c:69:9: Taking true branch
    67. 
    68.     /* let's disallow possible ambiguous cases */
    69.     if (size > (INT_MAX - 32) || !size)
                ^
    70.         return NULL;
    71. 

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

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

libavutil/mem.c:161:9: Taking false branch
  159. {
  160.     void *ptr = av_malloc(size);
  161.     if (ptr)
               ^
  162.         memset(ptr, 0, size);
  163.     return ptr;

libavutil/mem.c:163:5: 
  161.     if (ptr)
  162.         memset(ptr, 0, size);
  163.     return ptr;
           ^
  164. }
  165. 

libavutil/mem.c:164:1: return from a call to av_mallocz
  162.         memset(ptr, 0, size);
  163.     return ptr;
  164. }
       ^
  165. 
  166. char *av_strdup(const char *s)

libavcodec/mpegvideo.c:875:5: Taking true branch
873.     yc_size = y_size + 2   * c_size;
874. 
875.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
         ^
876.                       fail); // error ressilience code looks cleaner with this
877.     for (y = 0; y < s->mb_height; y++)

libavcodec/mpegvideo.c:875:5: Taking false branch
873.     yc_size = y_size + 2   * c_size;
874. 
875.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
         ^
876.                       fail); // error ressilience code looks cleaner with this
877.     for (y = 0; y < s->mb_height; y++)

libavcodec/mpegvideo.c:877:10: 
875.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
876.                       fail); // error ressilience code looks cleaner with this
877.     for (y = 0; y < s->mb_height; y++)
              ^
878.         for (x = 0; x < s->mb_width; x++)
879.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;

libavcodec/mpegvideo.c:877:17: Loop condition is false. Leaving loop
875.     FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
876.                       fail); // error ressilience code looks cleaner with this
877.     for (y = 0; y < s->mb_height; y++)
                     ^
878.         for (x = 0; x < s->mb_width; x++)
879.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;

libavcodec/mpegvideo.c:881:5: 
879.             s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;
880. 
881.     s->mb_index2xy[s->mb_height * s->mb_width] =
         ^
882.         (s->mb_height - 1) * s->mb_stride + s->mb_width; // FIXME really needed?
883. 

static int init_context_frame(MpegEncContext *s)
{
    int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;
    s->mb_width   = (s->width + 15) / 16;
    s->mb_stride  = s->mb_width + 1;
    s->b8_stride  = s->mb_width * 2 + 1;
    s->b4_stride  = s->mb_width * 4 + 1;
    mb_array_size = s->mb_height * s->mb_stride;
    mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;
    s->h_edge_pos = s->mb_width * 16;
    s->v_edge_pos = s->mb_height * 16;
    s->mb_num     = s->mb_width * s->mb_height;
    s->block_wrap[0] =
    s->block_wrap[1] =
    s->block_wrap[2] =
    s->block_wrap[3] = s->b8_stride;
    s->block_wrap[4] =
    s->block_wrap[5] = s->mb_stride;
    y_size  = s->b8_stride * (2 * s->mb_height + 1);
    c_size  = s->mb_stride * (s->mb_height + 1);
    yc_size = y_size + 2   * c_size;
    FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),
                      fail);
    for (y = 0; y < s->mb_height; y++)
        for (x = 0; x < s->mb_width; x++)
            s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;
    s->mb_index2xy[s->mb_height * s->mb_width] =
        (s->mb_height - 1) * s->mb_stride + s->mb_width;
    if (s->encoding) {
        FF_ALLOCZ_OR_GOTO(s->avctx, s->p_mv_table_base,
                          mv_table_size * 2 * sizeof(int16_t), fail);
        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_forw_mv_table_base,
                          mv_table_size * 2 * sizeof(int16_t), fail);
        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_back_mv_table_base,
                          mv_table_size * 2 * sizeof(int16_t), fail);
        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_bidir_forw_mv_table_base,
                          mv_table_size * 2 * sizeof(int16_t), fail);
        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_bidir_back_mv_table_base,
                          mv_table_size * 2 * sizeof(int16_t), fail);
        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_direct_mv_table_base,
                          mv_table_size * 2 * sizeof(int16_t), fail);
        s->p_mv_table            = s->p_mv_table_base + s->mb_stride + 1;
        s->b_forw_mv_table       = s->b_forw_mv_table_base + s->mb_stride + 1;
        s->b_back_mv_table       = s->b_back_mv_table_base + s->mb_stride + 1;
        s->b_bidir_forw_mv_table = s->b_bidir_forw_mv_table_base +
                                   s->mb_stride + 1;
        s->b_bidir_back_mv_table = s->b_bidir_back_mv_table_base +
                                   s->mb_stride + 1;
        s->b_direct_mv_table     = s->b_direct_mv_table_base + s->mb_stride + 1;
        FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_type, mb_array_size *
                          sizeof(uint16_t), fail);
        FF_ALLOCZ_OR_GOTO(s->avctx, s->lambda_table, mb_array_size *
                          sizeof(int), fail);
        FF_ALLOC_OR_GOTO(s->avctx, s->cplx_tab,
                         mb_array_size * sizeof(float), fail);
        FF_ALLOC_OR_GOTO(s->avctx, s->bits_tab,
                         mb_array_size * sizeof(float), fail);
    }
    if (s->codec_id == AV_CODEC_ID_MPEG4 ||
        (s->flags & CODEC_FLAG_INTERLACED_ME)) {
        for (i = 0; i < 2; i++) {
            int j, k;
            for (j = 0; j < 2; j++) {
                for (k = 0; k < 2; k++) {
                    FF_ALLOCZ_OR_GOTO(s->avctx,
                                      s->b_field_mv_table_base[i][j][k],
                                      mv_table_size * 2 * sizeof(int16_t),
                                      fail);
                    s->b_field_mv_table[i][j][k] = s->b_field_mv_table_base[i][j][k] +
                                                   s->mb_stride + 1;
                }
                FF_ALLOCZ_OR_GOTO(s->avctx, s->b_field_select_table [i][j],
                                  mb_array_size * 2 * sizeof(uint8_t), fail);
                FF_ALLOCZ_OR_GOTO(s->avctx, s->p_field_mv_table_base[i][j],
                                  mv_table_size * 2 * sizeof(int16_t), fail);
                s->p_field_mv_table[i][j] = s->p_field_mv_table_base[i][j]
                                            + s->mb_stride + 1;
            }
            FF_ALLOCZ_OR_GOTO(s->avctx, s->p_field_select_table[i],
                              mb_array_size * 2 * sizeof(uint8_t), fail);
        }
    }
    if (s->out_format == FMT_H263) {
        FF_ALLOCZ_OR_GOTO(s->avctx, s->coded_block_base, y_size, fail);
        s->coded_block = s->coded_block_base + s->b8_stride + 1;
        FF_ALLOCZ_OR_GOTO(s->avctx, s->cbp_table,
                          mb_array_size * sizeof(uint8_t), fail);
        FF_ALLOCZ_OR_GOTO(s->avctx, s->pred_dir_table,
                          mb_array_size * sizeof(uint8_t), fail);
    }
    if (s->h263_pred || s->h263_plus || !s->encoding) {
        FF_ALLOCZ_OR_GOTO(s->avctx, s->dc_val_base,
                          yc_size * sizeof(int16_t), fail);
        s->dc_val[0] = s->dc_val_base + s->b8_stride + 1;
        s->dc_val[1] = s->dc_val_base + y_size + s->mb_stride + 1;
        s->dc_val[2] = s->dc_val[1] + c_size;
        for (i = 0; i < yc_size; i++)
            s->dc_val_base[i] = 1024;
    }
    FF_ALLOCZ_OR_GOTO(s->avctx, s->mbintra_table, mb_array_size, fail);
    memset(s->mbintra_table, 1, mb_array_size);
    FF_ALLOCZ_OR_GOTO(s->avctx, s->mbskip_table, mb_array_size + 2, fail);
    return init_er(s);
fail:
    return AVERROR(ENOMEM);
}
['static int init_context_frame(MpegEncContext *s)\n{\n    int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;\n    s->mb_width   = (s->width + 15) / 16;\n    s->mb_stride  = s->mb_width + 1;\n    s->b8_stride  = s->mb_width * 2 + 1;\n    s->b4_stride  = s->mb_width * 4 + 1;\n    mb_array_size = s->mb_height * s->mb_stride;\n    mv_table_size = (s->mb_height + 2) * s->mb_stride + 1;\n    s->h_edge_pos = s->mb_width * 16;\n    s->v_edge_pos = s->mb_height * 16;\n    s->mb_num     = s->mb_width * s->mb_height;\n    s->block_wrap[0] =\n    s->block_wrap[1] =\n    s->block_wrap[2] =\n    s->block_wrap[3] = s->b8_stride;\n    s->block_wrap[4] =\n    s->block_wrap[5] = s->mb_stride;\n    y_size  = s->b8_stride * (2 * s->mb_height + 1);\n    c_size  = s->mb_stride * (s->mb_height + 1);\n    yc_size = y_size + 2   * c_size;\n    FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_index2xy, (s->mb_num + 1) * sizeof(int),\n                      fail);\n    for (y = 0; y < s->mb_height; y++)\n        for (x = 0; x < s->mb_width; x++)\n            s->mb_index2xy[x + y * s->mb_width] = x + y * s->mb_stride;\n    s->mb_index2xy[s->mb_height * s->mb_width] =\n        (s->mb_height - 1) * s->mb_stride + s->mb_width;\n    if (s->encoding) {\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->p_mv_table_base,\n                          mv_table_size * 2 * sizeof(int16_t), fail);\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_forw_mv_table_base,\n                          mv_table_size * 2 * sizeof(int16_t), fail);\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_back_mv_table_base,\n                          mv_table_size * 2 * sizeof(int16_t), fail);\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_bidir_forw_mv_table_base,\n                          mv_table_size * 2 * sizeof(int16_t), fail);\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_bidir_back_mv_table_base,\n                          mv_table_size * 2 * sizeof(int16_t), fail);\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->b_direct_mv_table_base,\n                          mv_table_size * 2 * sizeof(int16_t), fail);\n        s->p_mv_table            = s->p_mv_table_base + s->mb_stride + 1;\n        s->b_forw_mv_table       = s->b_forw_mv_table_base + s->mb_stride + 1;\n        s->b_back_mv_table       = s->b_back_mv_table_base + s->mb_stride + 1;\n        s->b_bidir_forw_mv_table = s->b_bidir_forw_mv_table_base +\n                                   s->mb_stride + 1;\n        s->b_bidir_back_mv_table = s->b_bidir_back_mv_table_base +\n                                   s->mb_stride + 1;\n        s->b_direct_mv_table     = s->b_direct_mv_table_base + s->mb_stride + 1;\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->mb_type, mb_array_size *\n                          sizeof(uint16_t), fail);\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->lambda_table, mb_array_size *\n                          sizeof(int), fail);\n        FF_ALLOC_OR_GOTO(s->avctx, s->cplx_tab,\n                         mb_array_size * sizeof(float), fail);\n        FF_ALLOC_OR_GOTO(s->avctx, s->bits_tab,\n                         mb_array_size * sizeof(float), fail);\n    }\n    if (s->codec_id == AV_CODEC_ID_MPEG4 ||\n        (s->flags & CODEC_FLAG_INTERLACED_ME)) {\n        for (i = 0; i < 2; i++) {\n            int j, k;\n            for (j = 0; j < 2; j++) {\n                for (k = 0; k < 2; k++) {\n                    FF_ALLOCZ_OR_GOTO(s->avctx,\n                                      s->b_field_mv_table_base[i][j][k],\n                                      mv_table_size * 2 * sizeof(int16_t),\n                                      fail);\n                    s->b_field_mv_table[i][j][k] = s->b_field_mv_table_base[i][j][k] +\n                                                   s->mb_stride + 1;\n                }\n                FF_ALLOCZ_OR_GOTO(s->avctx, s->b_field_select_table [i][j],\n                                  mb_array_size * 2 * sizeof(uint8_t), fail);\n                FF_ALLOCZ_OR_GOTO(s->avctx, s->p_field_mv_table_base[i][j],\n                                  mv_table_size * 2 * sizeof(int16_t), fail);\n                s->p_field_mv_table[i][j] = s->p_field_mv_table_base[i][j]\n                                            + s->mb_stride + 1;\n            }\n            FF_ALLOCZ_OR_GOTO(s->avctx, s->p_field_select_table[i],\n                              mb_array_size * 2 * sizeof(uint8_t), fail);\n        }\n    }\n    if (s->out_format == FMT_H263) {\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->coded_block_base, y_size, fail);\n        s->coded_block = s->coded_block_base + s->b8_stride + 1;\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->cbp_table,\n                          mb_array_size * sizeof(uint8_t), fail);\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->pred_dir_table,\n                          mb_array_size * sizeof(uint8_t), fail);\n    }\n    if (s->h263_pred || s->h263_plus || !s->encoding) {\n        FF_ALLOCZ_OR_GOTO(s->avctx, s->dc_val_base,\n                          yc_size * sizeof(int16_t), fail);\n        s->dc_val[0] = s->dc_val_base + s->b8_stride + 1;\n        s->dc_val[1] = s->dc_val_base + y_size + s->mb_stride + 1;\n        s->dc_val[2] = s->dc_val[1] + c_size;\n        for (i = 0; i < yc_size; i++)\n            s->dc_val_base[i] = 1024;\n    }\n    FF_ALLOCZ_OR_GOTO(s->avctx, s->mbintra_table, mb_array_size, fail);\n    memset(s->mbintra_table, 1, mb_array_size);\n    FF_ALLOCZ_OR_GOTO(s->avctx, s->mbskip_table, mb_array_size + 2, fail);\n    return init_er(s);\nfail:\n    return AVERROR(ENOMEM);\n}', 'void *av_mallocz(size_t size)\n{\n    void *ptr = av_malloc(size);\n    if (ptr)\n        memset(ptr, 0, size);\n    return ptr;\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) || !size)\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_ALIGNED_MALLOC\n    ptr = _aligned_malloc(size, 32);\n#elif HAVE_MEMALIGN\n    ptr = memalign(32, size);\n#else\n    ptr = malloc(size);\n#endif\n    return ptr;\n}']