int check_intra_pred8x8_mode_emuedge(int mode, int mb_x, int mb_y, int vp7)
{
    switch (mode) {
    case DC_PRED8x8:
        return check_dc_pred8x8_mode(mode, mb_x, mb_y);
    case VERT_PRED8x8:
        return !mb_y ? (vp7 ? DC_128_PRED8x8 : DC_127_PRED8x8) : mode;
    case HOR_PRED8x8:
        return !mb_x ? (vp7 ? DC_128_PRED8x8 : DC_129_PRED8x8) : mode;
    case PLANE_PRED8x8: /* TM */
        return check_tm_pred8x8_mode(mode, mb_x, mb_y, vp7);
    }
    return mode;
}

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.