Currently, DM MR registration flow doesn't set the mlx5_ib_dev pointer and
can cause a NULL pointer dereference if userspace dumps the MR via rdma
tool.
Assign the IB device together with the other fields and remove the
redundant reference of mlx5_ib_dev from mlx5_ib_mr.
Cc: stable@vger.kernel.org Fixes: 6c29f57ea475 ("IB/mlx5: Device memory mr registration support") Link: https://lore.kernel.org/r/20201203190807.127189-1-leon@kernel.org Signed-off-by: Maor Gottlieb <maorg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>