static int vp8_lossy_decode_alpha(AVCodecContext *avctx, AVFrame *p,
                                  uint8_t *data_start,
                                  unsigned int data_size)
{
    WebPContext *s = avctx->priv_data;
    int x, y, ret;

    if (s->alpha_compression == ALPHA_COMPRESSION_NONE) {
        GetByteContext gb;

        bytestream2_init(&gb, data_start, data_size);
        for (y = 0; y < s->height; y++)
            bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y,
                                   s->width);
    } else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) {
        uint8_t *ap, *pp;
        int alpha_got_frame = 0;

        s->alpha_frame = av_frame_alloc();
        if (!s->alpha_frame)
            return AVERROR(ENOMEM);

        ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame,
                                        data_start, data_size, 1);
        if (ret < 0) {
            av_frame_free(&s->alpha_frame);
            return ret;
        }
        if (!alpha_got_frame) {
            av_frame_free(&s->alpha_frame);
            return AVERROR_INVALIDDATA;
        }

        /* copy green component of alpha image to alpha plane of primary image */
        for (y = 0; y < s->height; y++) {
            ap = GET_PIXEL(s->alpha_frame, 0, y) + 2;
            pp = p->data[3] + p->linesize[3] * y;
            for (x = 0; x < s->width; x++) {
                *pp = *ap;
                pp++;
                ap += 4;
            }
        }
        av_frame_free(&s->alpha_frame);
    }

    /* apply alpha filtering */
    if (s->alpha_filter)
        alpha_inverse_prediction(p, s->alpha_filter);

    return 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.