[PATCH v2 56/63] RDMA/mlx5: Use struct_group() to zero struct mlx5_ib_mr

[Kees Cook]

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Add struct_group() to mark region of struct mlx5_ib_mr that should be
initialized to zero.

Cc: Leon Romanovsky <l...@kernel.org>
Cc: Doug Ledford <dledf...@redhat.com>
Cc: Jason Gunthorpe <j...@ziepe.ca>
Cc: linux-r...@vger.kernel.org
Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 drivers/infiniband/hw/mlx5/mlx5_ib.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h 
b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index bf20a388eabe..f63bf204a7a1 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -644,6 +644,7 @@ struct mlx5_ib_mr {
        struct ib_umem *umem;
 
        /* This is zero'd when the MR is allocated */
+       struct_group(cleared,
        union {
                /* Used only while the MR is in the cache */
                struct {
@@ -691,12 +692,13 @@ struct mlx5_ib_mr {
                        bool is_odp_implicit;
                };
        };
+       );
 };
 
 /* Zero the fields in the mr that are variant depending on usage */
 static inline void mlx5_clear_mr(struct mlx5_ib_mr *mr)
 {
-       memset(mr->out, 0, sizeof(*mr) - offsetof(struct mlx5_ib_mr, out));
+       memset(&mr->cleared, 0, sizeof(mr->cleared));
 }
 
 static inline bool is_odp_mr(struct mlx5_ib_mr *mr)
-- 
2.30.2