void prefetch_motion(VP8Context *s, VP8Macroblock *mb, int mb_x, int mb_y,
                     int mb_xy, int ref)
{
    /* Don't prefetch refs that haven't been used very often this frame. */
    if (s->ref_count[ref - 1] > (mb_xy >> 5)) {
        int x_off = mb_x << 4, y_off = mb_y << 4;
        int mx = (mb->mv.x >> 2) + x_off + 8;
        int my = (mb->mv.y >> 2) + y_off;
        uint8_t **src = s->framep[ref]->tf.f->data;
        int off = mx + (my + (mb_x & 3) * 4) * s->linesize + 64;
        /* For threading, a ff_thread_await_progress here might be useful, but
         * it actually slows down the decoder. Since a bad prefetch doesn't
         * generate bad decoder output, we don't run it here. */
        s->vdsp.prefetch(src[0] + off, s->linesize, 4);
        off = (mx >> 1) + ((my >> 1) + (mb_x & 7)) * s->uvlinesize + 64;
        s->vdsp.prefetch(src[1] + off, src[2] - src[1], 2);
    }
}

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.