[PATCH 4.16 103/196] RDMA/mlx5: Protect from NULL pointer derefence

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Leon Romanovsky <leonro@xxxxxxxxxxxx>

commit 4289861d88d6c7b5e4c8cc7fe2ad6cdf0cdfc366 upstream.

The mlx5_ib_alloc_implicit_mr() can fail to acquire pages
and the returned mr pointer won't be valid. Ensure that it
is not error prior to access.

Cc: <stable@xxxxxxxxxxxxxxx> # 4.10
Fixes: 81713d3788d2 ("IB/mlx5: Add implicit MR support")
Reported-by: Noa Osherovich <noaos@xxxxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/hw/mlx5/mr.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1223,6 +1223,8 @@ struct ib_mr *mlx5_ib_reg_user_mr(struct
 			return ERR_PTR(-EINVAL);
 
 		mr = mlx5_ib_alloc_implicit_mr(to_mpd(pd), access_flags);
+		if (IS_ERR(mr))
+			return ERR_CAST(mr);
 		return &mr->ibmr;
 	}
 #endif