RDMA/mlx5: Fix integer overflow while resizing CQ

The user can provide very large cqe_size which will cause to integer
overflow as it can be seen in the following UBSAN warning:
Signed-off-by: NDoug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/cq.c

@@ -1178,7 +1178,12 @@ static int resize_user(struct mlx5_ib_dev *dev, struct mlx5_ib_cq *cq,
 	if (ucmd.reserved0 || ucmd.reserved1)
 		return -EINVAL;
 
-	umem = ib_umem_get(context, ucmd.buf_addr, entries * ucmd.cqe_size,
+	/* check multiplication overflow */
+	if (ucmd.cqe_size && SIZE_MAX / ucmd.cqe_size <= entries - 1)
+		return -EINVAL;
+
+	umem = ib_umem_get(context, ucmd.buf_addr,
+			   (size_t)ucmd.cqe_size * entries,
 			   IB_ACCESS_LOCAL_WRITE, 1);
 	if (IS_ERR(umem)) {
 		err = PTR_ERR(umem);