From: Kees Cook <keescook@chromium.org>
Date: Mon, 13 Dec 2021 14:33:23 -0800
Subject: RDMA/mlx5: Use memset_after() to zero struct mlx5_ib_mr
Patch-mainline: v5.17-rc1
Git-commit: e517f76a3cb24b2a4749e0348390aece24cf9925
References: jsc#PED-1552

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.

Link: https://lore.kernel.org/r/20211213223331.135412-10-keescook@chromium.org
Acked-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/infiniband/hw/mlx5/mlx5_ib.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -665,9 +665,9 @@ struct mlx5_ib_mr {
 
 	/* User MR data */
 	struct mlx5_cache_ent *cache_ent;
+	/* Everything after cache_ent is zero'd when MR allocated */
 	struct ib_umem *umem;
 
-	/* This is zero'd when the MR is allocated */
 	union {
 		/* Used only while the MR is in the cache */
 		struct {
@@ -719,7 +719,7 @@ 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)