void vp7_decode_mvs(VP8Context *s, VP8Macroblock *mb,
                    int mb_x, int mb_y, int layout)
{
    VP8Macroblock *mb_edge[12];
    enum { CNT_ZERO, CNT_NEAREST, CNT_NEAR };
    enum { VP8_EDGE_TOP, VP8_EDGE_LEFT, VP8_EDGE_TOPLEFT };
    int idx = CNT_ZERO;
    VP56mv near_mv[3];
    uint8_t cnt[3] = { 0 };
    VP56RangeCoder *c = &s->c;
    int i;

    AV_ZERO32(&near_mv[0]);
    AV_ZERO32(&near_mv[1]);
    AV_ZERO32(&near_mv[2]);

    for (i = 0; i < VP7_MV_PRED_COUNT; i++) {
        const VP7MVPred * pred = &vp7_mv_pred[i];
        int edge_x, edge_y;

        if (vp7_calculate_mb_offset(mb_x, mb_y, s->mb_width, pred->xoffset,
                                    pred->yoffset, !s->profile, &edge_x, &edge_y)) {
            VP8Macroblock *edge = mb_edge[i] = (s->mb_layout == 1)
                                             ? s->macroblocks_base + 1 + edge_x +
                                               (s->mb_width + 1) * (edge_y + 1)
                                             : s->macroblocks + edge_x +
                                               (s->mb_height - edge_y - 1) * 2;
            uint32_t mv = AV_RN32A(get_bmv_ptr(edge, vp7_mv_pred[i].subblock));
            if (mv) {
                if (AV_RN32A(&near_mv[CNT_NEAREST])) {
                    if (mv == AV_RN32A(&near_mv[CNT_NEAREST])) {
                        idx = CNT_NEAREST;
                    } else if (AV_RN32A(&near_mv[CNT_NEAR])) {
                        if (mv != AV_RN32A(&near_mv[CNT_NEAR]))
                            continue;
                        idx = CNT_NEAR;
                    } else {
                        AV_WN32A(&near_mv[CNT_NEAR], mv);
                        idx = CNT_NEAR;
                    }
                } else {
                    AV_WN32A(&near_mv[CNT_NEAREST], mv);
                    idx = CNT_NEAREST;
                }
            } else {
                idx = CNT_ZERO;
            }
        } else {
            idx = CNT_ZERO;
        }
        cnt[idx] += vp7_mv_pred[i].score;
    }

    mb->partitioning = VP8_SPLITMVMODE_NONE;

    if (vp56_rac_get_prob_branchy(c, vp7_mode_contexts[cnt[CNT_ZERO]][0])) {
        mb->mode = VP8_MVMODE_MV;

        if (vp56_rac_get_prob_branchy(c, vp7_mode_contexts[cnt[CNT_NEAREST]][1])) {

            if (vp56_rac_get_prob_branchy(c, vp7_mode_contexts[cnt[CNT_NEAR]][2])) {

                if (cnt[CNT_NEAREST] > cnt[CNT_NEAR])
                    AV_WN32A(&mb->mv, cnt[CNT_ZERO] > cnt[CNT_NEAREST] ? 0 : AV_RN32A(&near_mv[CNT_NEAREST]));
                else
                    AV_WN32A(&mb->mv, cnt[CNT_ZERO] > cnt[CNT_NEAR]    ? 0 : AV_RN32A(&near_mv[CNT_NEAR]));

                if (vp56_rac_get_prob_branchy(c, vp7_mode_contexts[cnt[CNT_NEAR]][3])) {
                    mb->mode = VP8_MVMODE_SPLIT;
                    mb->mv = mb->bmv[decode_splitmvs(s, c, mb, layout, IS_VP7) - 1];
                } else {
                    mb->mv.y += vp7_read_mv_component(c, s->prob->mvc[0]);
                    mb->mv.x += vp7_read_mv_component(c, s->prob->mvc[1]);
                    mb->bmv[0] = mb->mv;
                }
            } else {
                mb->mv = near_mv[CNT_NEAR];
                mb->bmv[0] = mb->mv;
            }
        } else {
            mb->mv = near_mv[CNT_NEAREST];
            mb->bmv[0] = mb->mv;
        }
    } else {
        mb->mode = VP8_MVMODE_ZERO;
        AV_ZERO32(&mb->mv);
        mb->bmv[0] = mb->mv;
    }
}

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.