static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
    AVFilterContext *ctx = inlink->dst;
    BoxBlurContext *s = ctx->priv;
    AVFilterLink *outlink = inlink->dst->outputs[0];
    AVFrame *out;
    int plane;
    int cw = FF_CEIL_RSHIFT(inlink->w, s->hsub), ch = FF_CEIL_RSHIFT(in->height, s->vsub);
    int w[4] = { inlink->w, cw, cw, inlink->w };
    int h[4] = { in->height, ch, ch, in->height };

    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
    if (!out) {
        av_frame_free(&in);
        return AVERROR(ENOMEM);
    }
    av_frame_copy_props(out, in);

    for (plane = 0; plane < 4 && in->data[plane] && in->linesize[plane]; plane++)
        hblur(out->data[plane], out->linesize[plane],
              in ->data[plane], in ->linesize[plane],
              w[plane], h[plane], s->radius[plane], s->power[plane],
              s->temp);

    for (plane = 0; plane < 4 && in->data[plane] && in->linesize[plane]; plane++)
        vblur(out->data[plane], out->linesize[plane],
              out->data[plane], out->linesize[plane],
              w[plane], h[plane], s->radius[plane], s->power[plane],
              s->temp);

    av_frame_free(&in);

    return ff_filter_frame(outlink, out);
}
The software performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer.