void decode_mb_mode(VP8Context *s, VP8mvbounds *mv_bounds,
                    VP8Macroblock *mb, int mb_x, int mb_y,
                    uint8_t *segment, uint8_t *ref, int layout, int is_vp7)
{
    VP56RangeCoder *c = &s->c;
    static const char *vp7_feature_name[] = { "q-index",
                                              "lf-delta",
                                              "partial-golden-update",
                                              "blit-pitch" };
    if (is_vp7) {
        int i;
        *segment = 0;
        for (i = 0; i < 4; i++) {
            if (s->feature_enabled[i]) {
                if (vp56_rac_get_prob_branchy(c, s->feature_present_prob[i])) {
                      int index = vp8_rac_get_tree(c, vp7_feature_index_tree,
                                                   s->feature_index_prob[i]);
                      av_log(s->avctx, AV_LOG_WARNING,
                             "Feature %s present in macroblock (value 0x%x)\n",
                             vp7_feature_name[i], s->feature_value[i][index]);
                }
           }
        }
    } else if (s->segmentation.update_map) {
        int bit  = vp56_rac_get_prob(c, s->prob->segmentid[0]);
        *segment = vp56_rac_get_prob(c, s->prob->segmentid[1+bit]) + 2*bit;
    } else if (s->segmentation.enabled)
        *segment = ref ? *ref : *segment;
    mb->segment = *segment;

    mb->skip = s->mbskip_enabled ? vp56_rac_get_prob(c, s->prob->mbskip) : 0;

    if (s->keyframe) {
        mb->mode = vp8_rac_get_tree(c, vp8_pred16x16_tree_intra,
                                    vp8_pred16x16_prob_intra);

        if (mb->mode == MODE_I4x4) {
            decode_intra4x4_modes(s, c, mb, mb_x, 1, layout);
        } else {
            const uint32_t modes = (is_vp7 ? vp7_pred4x4_mode
                                           : vp8_pred4x4_mode)[mb->mode] * 0x01010101u;
            if (s->mb_layout)
                AV_WN32A(mb->intra4x4_pred_mode_top, modes);
            else
                AV_WN32A(s->intra4x4_pred_mode_top + 4 * mb_x, modes);
            AV_WN32A(s->intra4x4_pred_mode_left, modes);
        }

        mb->chroma_pred_mode = vp8_rac_get_tree(c, vp8_pred8x8c_tree,
                                                vp8_pred8x8c_prob_intra);
        mb->ref_frame        = VP56_FRAME_CURRENT;
    } else if (vp56_rac_get_prob_branchy(c, s->prob->intra)) {
        if (vp56_rac_get_prob_branchy(c, s->prob->last))
            mb->ref_frame =
                (!is_vp7 && vp56_rac_get_prob(c, s->prob->golden)) ? VP56_FRAME_GOLDEN2 /* altref */
                                                                   : VP56_FRAME_GOLDEN;
        else
            mb->ref_frame = VP56_FRAME_PREVIOUS;
        s->ref_count[mb->ref_frame - 1]++;

        if (is_vp7)
            vp7_decode_mvs(s, mb, mb_x, mb_y, layout);
        else
            vp8_decode_mvs(s, mv_bounds, mb, mb_x, mb_y, layout);
    } else {
        mb->mode = vp8_rac_get_tree(c, vp8_pred16x16_tree_inter, s->prob->pred16x16);

        if (mb->mode == MODE_I4x4)
            decode_intra4x4_modes(s, c, mb, mb_x, 0, layout);

        mb->chroma_pred_mode = vp8_rac_get_tree(c, vp8_pred8x8c_tree,
                                                s->prob->pred8x8c);
        mb->ref_frame        = VP56_FRAME_CURRENT;
        mb->partitioning     = VP8_SPLITMVMODE_NONE;
        AV_ZERO32(&mb->bmv[0]);
    }
}

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.