int mlx5_ib_read_user_wqe(struct mlx5_ib_qp *qp, int send, int wqe_index,
			  void *buffer, u32 length,
			  struct mlx5_ib_qp_base *base)
{
	struct ib_device *ibdev = qp->ibqp.device;
	struct mlx5_ib_dev *dev = to_mdev(ibdev);
	struct mlx5_ib_wq *wq = send ? &qp->sq : &qp->rq;
	size_t offset;
	size_t wq_end;
	struct ib_umem *umem = base->ubuffer.umem;
	u32 first_copy_length;
	int wqe_length;
	int ret;

	if (wq->wqe_cnt == 0) {
		mlx5_ib_dbg(dev, "mlx5_ib_read_user_wqe for a QP with wqe_cnt == 0. qp_type: 0x%x\n",
			    qp->ibqp.qp_type);
		return -EINVAL;
	}

	offset = wq->offset + ((wqe_index % wq->wqe_cnt) << wq->wqe_shift);
	wq_end = wq->offset + (wq->wqe_cnt << wq->wqe_shift);

	if (send && length < sizeof(struct mlx5_wqe_ctrl_seg))
		return -EINVAL;

	if (offset > umem->length ||
	    (send && offset + sizeof(struct mlx5_wqe_ctrl_seg) > umem->length))
		return -EINVAL;

	first_copy_length = min_t(u32, offset + length, wq_end) - offset;
	ret = ib_umem_copy_from(buffer, umem, offset, first_copy_length);
	if (ret)
		return ret;

	if (send) {
		struct mlx5_wqe_ctrl_seg *ctrl = buffer;
		int ds = be32_to_cpu(ctrl->qpn_ds) & MLX5_WQE_CTRL_DS_MASK;

		wqe_length = ds * MLX5_WQE_DS_UNITS;
	} else {
		wqe_length = 1 << wq->wqe_shift;
	}

	if (wqe_length <= first_copy_length)
		return first_copy_length;

	ret = ib_umem_copy_from(buffer + first_copy_length, umem, wq->offset,
				wqe_length - first_copy_length);
	if (ret)
		return ret;

	return wqe_length;
}

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.