static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,
                                     int *got_frame, uint8_t *data_start,
                                     unsigned int data_size, int is_alpha_chunk)
{
    WebPContext *s = avctx->priv_data;
    int w, h, ret, i, used;

    if (!is_alpha_chunk) {
        s->lossless = 1;
        avctx->pix_fmt = AV_PIX_FMT_ARGB;
    }

    ret = init_get_bits8(&s->gb, data_start, data_size);
    if (ret < 0)
        return ret;

    if (!is_alpha_chunk) {
        if (get_bits(&s->gb, 8) != 0x2F) {
            av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n");
            return AVERROR_INVALIDDATA;
        }

        w = get_bits(&s->gb, 14) + 1;
        h = get_bits(&s->gb, 14) + 1;

        update_canvas_size(avctx, w, h);

        ret = ff_set_dimensions(avctx, s->width, s->height);
        if (ret < 0)
            return ret;

        s->has_alpha = get_bits1(&s->gb);

        if (get_bits(&s->gb, 3) != 0x0) {
            av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n");
            return AVERROR_INVALIDDATA;
        }
    } else {
        if (!s->width || !s->height)
            return AVERROR_BUG;
        w = s->width;
        h = s->height;
    }

    /* parse transformations */
    s->nb_transforms = 0;
    s->reduced_width = 0;
    used = 0;
    while (get_bits1(&s->gb)) {
        enum TransformType transform = get_bits(&s->gb, 2);
        if (used & (1 << transform)) {
            av_log(avctx, AV_LOG_ERROR, "Transform %d used more than once\n",
                   transform);
            ret = AVERROR_INVALIDDATA;
            goto free_and_return;
        }
        used |= (1 << transform);
        s->transforms[s->nb_transforms++] = transform;
        switch (transform) {
        case PREDICTOR_TRANSFORM:
            ret = parse_transform_predictor(s);
            break;
        case COLOR_TRANSFORM:
            ret = parse_transform_color(s);
            break;
        case COLOR_INDEXING_TRANSFORM:
            ret = parse_transform_color_indexing(s);
            break;
        }
        if (ret < 0)
            goto free_and_return;
    }

    /* decode primary image */
    s->image[IMAGE_ROLE_ARGB].frame = p;
    if (is_alpha_chunk)
        s->image[IMAGE_ROLE_ARGB].is_alpha_primary = 1;
    ret = decode_entropy_coded_image(s, IMAGE_ROLE_ARGB, w, h);
    if (ret < 0)
        goto free_and_return;

    /* apply transformations */
    for (i = s->nb_transforms - 1; i >= 0; i--) {
        switch (s->transforms[i]) {
        case PREDICTOR_TRANSFORM:
            ret = apply_predictor_transform(s);
            break;
        case COLOR_TRANSFORM:
            ret = apply_color_transform(s);
            break;
        case SUBTRACT_GREEN:
            ret = apply_subtract_green_transform(s);
            break;
        case COLOR_INDEXING_TRANSFORM:
            ret = apply_color_indexing_transform(s);
            break;
        }
        if (ret < 0)
            goto free_and_return;
    }

    *got_frame   = 1;
    p->pict_type = AV_PICTURE_TYPE_I;
    p->key_frame = 1;
    ret          = data_size;

free_and_return:
    for (i = 0; i < IMAGE_ROLE_NB; i++)
        image_ctx_free(&s->image[i]);

    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.