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From:   Kees Cook <keescook@chromium.org>
To:     Ido Schimmel <idosch@nvidia.com>
Cc:     Kees Cook <keescook@chromium.org>, Petr Machata <petrm@nvidia.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org
Subject: [PATCH] mlxsw: spectrum_router: Replace 0-length array with flexible array
Date:   Thu,  5 Jan 2023 15:22:29 -0800
Message-Id: <20230105232224.never.150-kees@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Zero-length arrays are deprecated[1]. Replace struct
mlxsw_sp_nexthop_group_info's "nexthops" 0-length array with a flexible
array. Detected with GCC 13, using -fstrict-flex-arrays=3:

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c: In function 'mlxsw_sp_nexthop_group_hash_obj':
drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:3278:38: warning: array subscript i is outside array bounds of 'struct mlxsw_sp_nexthop[0]' [-Warray-bounds=]
 3278 |                         val ^= jhash(&nh->ifindex, sizeof(nh->ifindex), seed);
      |                                      ^~~~~~~~~~~~
drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:2954:33: note: while referencing 'nexthops'
 2954 |         struct mlxsw_sp_nexthop nexthops[0];
      |                                 ^~~~~~~~

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays

Cc: Ido Schimmel <idosch@nvidia.com>
Cc: Petr Machata <petrm@nvidia.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index c22c3ac4e2a1..09e32778b012 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -2951,7 +2951,7 @@ struct mlxsw_sp_nexthop_group_info {
 	   gateway:1, /* routes using the group use a gateway */
 	   is_resilient:1;
 	struct list_head list; /* member in nh_res_grp_list */
-	struct mlxsw_sp_nexthop nexthops[0];
+	struct mlxsw_sp_nexthop nexthops[];
 #define nh_rif	nexthops[0].rif
 };
 
-- 
2.34.1