[PATCH 09/17] RDMA/mlx5: Use memset_after() to zero struct mlx5_ib_mr

Kees Cook
2021-12-13T22:34:18Z

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

Use memset_after() to zero the end of struct mlx5_ib_mr that should
be initialized.

Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-rdma@vger.kernel.org
Acked-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/lkml/YbByJSkBgLRp5S8V@unreal
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/infiniband/hw/mlx5/mlx5_ib.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 4a7a56ed740b..ded10719b643 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -664,8 +664,8 @@ struct mlx5_ib_mr {

/* User MR data */
struct mlx5_cache_ent *cache_ent;
+ /* Everything after cache_ent is zero'd when MR allocated */

- /* This is zero'd when the MR is allocated */
union {
/* Used only while the MR is in the cache */
struct {
@@ -718,7 +718,7 @@ struct mlx5_ib_mr {
/* 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_after(mr, 0, cache_ent);
}

static inline bool is_odp_mr(struct mlx5_ib_mr *mr)
--
2.30.2