linux-hardening - [PATCH 55/64] RDMA/mlx5: Use struct_group() to zero struct mlx5_ib

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Date:   Tue, 27 Jul 2021 13:58:46 -0700
From:   Kees Cook <keescook@...omium.org>
To:     linux-hardening@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Keith Packard <keithpac@...zon.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-staging@...ts.linux.dev, linux-block@...r.kernel.org,
        linux-kbuild@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: [PATCH 55/64] RDMA/mlx5: Use struct_group() to zero struct mlx5_ib_mr

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.

Signed-off-by: Kees Cook <keescook@...omium.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 585fb00bdce8..830066e95260 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