int vp78_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                      AVPacket *avpkt, int is_vp7)
{
    VP8Context *s = avctx->priv_data;
    int ret, i, referenced, num_jobs;
     enum AVDiscard skip_thresh;
     VP8Frame *av_uninit(curframe), *prev_frame;
 
    av_assert0(avctx->pix_fmt == AV_PIX_FMT_YUVA420P || avctx->pix_fmt == AV_PIX_FMT_YUV420P);

     if (is_vp7)
         ret = vp7_decode_frame_header(s, avpkt->data, avpkt->size);
     else
        ret = vp8_decode_frame_header(s, avpkt->data, avpkt->size);

    if (ret < 0)
        goto err;

    prev_frame = s->framep[VP56_FRAME_CURRENT];

    referenced = s->update_last || s->update_golden == VP56_FRAME_CURRENT ||
                 s->update_altref == VP56_FRAME_CURRENT;

    skip_thresh = !referenced ? AVDISCARD_NONREF
                              : !s->keyframe ? AVDISCARD_NONKEY
                                             : AVDISCARD_ALL;

    if (avctx->skip_frame >= skip_thresh) {
        s->invisible = 1;
        memcpy(&s->next_framep[0], &s->framep[0], sizeof(s->framep[0]) * 4);
        goto skip_decode;
    }
    s->deblock_filter = s->filter.level && avctx->skip_loop_filter < skip_thresh;

    for (i = 0; i < 5; i++)
        if (s->frames[i].tf.f->data[0] &&
            &s->frames[i] != prev_frame &&
            &s->frames[i] != s->framep[VP56_FRAME_PREVIOUS] &&
            &s->frames[i] != s->framep[VP56_FRAME_GOLDEN]   &&
            &s->frames[i] != s->framep[VP56_FRAME_GOLDEN2])
            vp8_release_frame(s, &s->frames[i]);

    curframe = s->framep[VP56_FRAME_CURRENT] = vp8_find_free_buffer(s);

    if (!s->colorspace)
        avctx->colorspace = AVCOL_SPC_BT470BG;
    if (s->fullrange)
        avctx->color_range = AVCOL_RANGE_JPEG;
    else
        avctx->color_range = AVCOL_RANGE_MPEG;

    /* Given that arithmetic probabilities are updated every frame, it's quite
     * likely that the values we have on a random interframe are complete
     * junk if we didn't start decode on a keyframe. So just don't display
     * anything rather than junk. */
    if (!s->keyframe && (!s->framep[VP56_FRAME_PREVIOUS] ||
                         !s->framep[VP56_FRAME_GOLDEN]   ||
                         !s->framep[VP56_FRAME_GOLDEN2])) {
        av_log(avctx, AV_LOG_WARNING,
               "Discarding interframe without a prior keyframe!\n");
        ret = AVERROR_INVALIDDATA;
        goto err;
    }

    curframe->tf.f->key_frame = s->keyframe;
    curframe->tf.f->pict_type = s->keyframe ? AV_PICTURE_TYPE_I
                                            : AV_PICTURE_TYPE_P;
    if ((ret = vp8_alloc_frame(s, curframe, referenced)) < 0)
        goto err;

    if (s->update_altref != VP56_FRAME_NONE)
        s->next_framep[VP56_FRAME_GOLDEN2] = s->framep[s->update_altref];
    else
        s->next_framep[VP56_FRAME_GOLDEN2] = s->framep[VP56_FRAME_GOLDEN2];

    if (s->update_golden != VP56_FRAME_NONE)
        s->next_framep[VP56_FRAME_GOLDEN] = s->framep[s->update_golden];
    else
        s->next_framep[VP56_FRAME_GOLDEN] = s->framep[VP56_FRAME_GOLDEN];

    if (s->update_last)
        s->next_framep[VP56_FRAME_PREVIOUS] = curframe;
    else
        s->next_framep[VP56_FRAME_PREVIOUS] = s->framep[VP56_FRAME_PREVIOUS];

    s->next_framep[VP56_FRAME_CURRENT] = curframe;

    if (avctx->codec->update_thread_context)
        ff_thread_finish_setup(avctx);

    s->linesize   = curframe->tf.f->linesize[0];
    s->uvlinesize = curframe->tf.f->linesize[1];

    memset(s->top_nnz, 0, s->mb_width * sizeof(*s->top_nnz));
    /* Zero macroblock structures for top/top-left prediction
     * from outside the frame. */
    if (!s->mb_layout)
        memset(s->macroblocks + s->mb_height * 2 - 1, 0,
               (s->mb_width + 1) * sizeof(*s->macroblocks));
    if (!s->mb_layout && s->keyframe)
        memset(s->intra4x4_pred_mode_top, DC_PRED, s->mb_width * 4);

    memset(s->ref_count, 0, sizeof(s->ref_count));

    if (s->mb_layout == 1) {
        if (prev_frame && s->segmentation.enabled &&
            !s->segmentation.update_map)
            ff_thread_await_progress(&prev_frame->tf, 1, 0);
        if (is_vp7)
            vp7_decode_mv_mb_modes(avctx, curframe, prev_frame);
        else
            vp8_decode_mv_mb_modes(avctx, curframe, prev_frame);
    }

    if (avctx->active_thread_type == FF_THREAD_FRAME)
        num_jobs = 1;
    else
        num_jobs = FFMIN(s->num_coeff_partitions, avctx->thread_count);
    s->num_jobs   = num_jobs;
    s->curframe   = curframe;
    s->prev_frame = prev_frame;
    s->mv_bounds.mv_min.y   = -MARGIN;
    s->mv_bounds.mv_max.y   = ((s->mb_height - 1) << 6) + MARGIN;
    for (i = 0; i < MAX_THREADS; i++) {
        VP8ThreadData *td = &s->thread_data[i];
        atomic_init(&td->thread_mb_pos, 0);
        atomic_init(&td->wait_mb_pos, INT_MAX);
    }
    if (is_vp7)
        avctx->execute2(avctx, vp7_decode_mb_row_sliced, s->thread_data, NULL,
                        num_jobs);
    else
        avctx->execute2(avctx, vp8_decode_mb_row_sliced, s->thread_data, NULL,
                        num_jobs);

    ff_thread_report_progress(&curframe->tf, INT_MAX, 0);
    memcpy(&s->framep[0], &s->next_framep[0], sizeof(s->framep[0]) * 4);

skip_decode:
    if (!s->update_probabilities)
        s->prob[0] = s->prob[1];

    if (!s->invisible) {
        if ((ret = av_frame_ref(data, curframe->tf.f)) < 0)
            return ret;
        *got_frame = 1;
    }

    return avpkt->size;
err:
    memcpy(&s->next_framep[0], &s->framep[0], sizeof(s->framep[0]) * 4);
    return ret;
}

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.