linux-hardening - [PATCH][next] RDMA/mlx4: Copy union directly

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Date:   Tue, 15 Aug 2023 14:39:53 -0600
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Yishai Hadas <yishaih@...dia.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>
Cc:     linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-hardening@...r.kernel.org
Subject: [PATCH][next] RDMA/mlx4: Copy union directly

Copy union directly instead of using memcpy().

Note that in this case, a direct assignment is more readable and
consistent with the subsequent assignments.

This addresses the following -Wstringop-overflow warning seen in s390
with defconfig:
drivers/infiniband/hw/mlx4/main.c:296:33: warning: writing 16 bytes into a region of size 0 [-Wstringop-overflow=]
  296 |                                 memcpy(&port_gid_table->gids[free].gid,
      |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  297 |                                        &attr->gid, sizeof(attr->gid));
      |                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This helps with the ongoing efforts to globally enable
-Wstringop-overflow.

Link: https://github.com/KSPP/linux/issues/308
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 drivers/infiniband/hw/mlx4/main.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c
index 216aacd72e4f..2d2cd17e02e6 100644
--- a/drivers/infiniband/hw/mlx4/main.c
+++ b/drivers/infiniband/hw/mlx4/main.c
@@ -293,8 +293,7 @@ static int mlx4_ib_add_gid(const struct ib_gid_attr *attr, void **context)
 				ret = -ENOMEM;
 			} else {
 				*context = port_gid_table->gids[free].ctx;
-				memcpy(&port_gid_table->gids[free].gid,
-				       &attr->gid, sizeof(attr->gid));
+				port_gid_table->gids[free].gid = attr->gid;
 				port_gid_table->gids[free].gid_type = attr->gid_type;
 				port_gid_table->gids[free].vlan_id = vlan_id;
 				port_gid_table->gids[free].ctx->real_index = free;
-- 
2.34.1