void decode_mb_coeffs(VP8Context *s, VP8ThreadData *td, VP56RangeCoder *c,
                      VP8Macroblock *mb, uint8_t t_nnz[9], uint8_t l_nnz[9],
                      int is_vp7)
{
    int i, x, y, luma_start = 0, luma_ctx = 3;
    int nnz_pred, nnz, nnz_total = 0;
    int segment = mb->segment;
    int block_dc = 0;

    if (mb->mode != MODE_I4x4 && (is_vp7 || mb->mode != VP8_MVMODE_SPLIT)) {
        nnz_pred = t_nnz[8] + l_nnz[8];

        nnz = decode_block_coeffs(c, td->block_dc, s->prob->token[1], 0,
                                  nnz_pred, s->qmat[segment].luma_dc_qmul,
                                  ff_zigzag_scan, is_vp7);
        l_nnz[8] = t_nnz[8] = !!nnz;

        if (is_vp7 && mb->mode > MODE_I4x4) {
            nnz |=  inter_predict_dc(td->block_dc,
                                     s->inter_dc_pred[mb->ref_frame - 1]);
        }

        if (nnz) {
            nnz_total += nnz;
            block_dc   = 1;
            if (nnz == 1)
                s->vp8dsp.vp8_luma_dc_wht_dc(td->block, td->block_dc);
            else
                s->vp8dsp.vp8_luma_dc_wht(td->block, td->block_dc);
        }
        luma_start = 1;
        luma_ctx   = 0;
    }

    for (y = 0; y < 4; y++)
        for (x = 0; x < 4; x++) {
            nnz_pred = l_nnz[y] + t_nnz[x];
            nnz = decode_block_coeffs(c, td->block[y][x],
                                      s->prob->token[luma_ctx],
                                      luma_start, nnz_pred,
                                      s->qmat[segment].luma_qmul,
                                      s->prob[0].scan, is_vp7);
            /* nnz+block_dc may be one more than the actual last index,
             * but we don't care */
            td->non_zero_count_cache[y][x] = nnz + block_dc;
            t_nnz[x] = l_nnz[y] = !!nnz;
            nnz_total += nnz;
        }

    for (i = 4; i < 6; i++)
        for (y = 0; y < 2; y++)
            for (x = 0; x < 2; x++) {
                nnz_pred = l_nnz[i + 2 * y] + t_nnz[i + 2 * x];
                nnz = decode_block_coeffs(c, td->block[i][(y << 1) + x],
                                          s->prob->token[2], 0, nnz_pred,
                                          s->qmat[segment].chroma_qmul,
                                          s->prob[0].scan, is_vp7);
                td->non_zero_count_cache[i][(y << 1) + x] = nnz;
                t_nnz[i + 2 * x] = l_nnz[i + 2 * y] = !!nnz;
                nnz_total += nnz;
            }

    if (!nnz_total)
        mb->skip = 1;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.