Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To:     Nathan Chancellor <nathan@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
CC:     Sergey Shtylyov <s.shtylyov@omp.ru>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-renesas-soc@vger.kernel.org" 
        <linux-renesas-soc@vger.kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, Kees Cook <keescook@chromium.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        "llvm@lists.linux.dev" <llvm@lists.linux.dev>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "patches@lists.linux.dev" <patches@lists.linux.dev>
Subject: RE: [PATCH net-next] net: ethernet: renesas: Fix return type of
 rswitch_start_xmit()
Thread-Topic: [PATCH net-next] net: ethernet: renesas: Fix return type of
 rswitch_start_xmit()
Thread-Index: AQHY78/AL5gpWhL7fkeU297Crrw2Ea4uIPvQ
Date:   Fri, 4 Nov 2022 04:29:42 +0000
Message-ID: <TYBPR01MB53419352217D1C2FC8DFE1AED83B9@TYBPR01MB5341.jpnprd01.prod.outlook.com>
References: <20221103220032.2142122-1-nathan@kernel.org>
In-Reply-To: <20221103220032.2142122-1-nathan@kernel.org>
Accept-Language: ja-JP, en-US
Content-Language: ja-JP
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?i+KaWJvgZ4Sr/Ith/Qb6A1V2oYugI+LaJA3zQ5gdyqoplNVicMPpqWDCKgQn?=
 =?us-ascii?Q?/l3oDzTXnSt/678Ti7Uh/vOPsYpBQGxtgH2mnalE0BduR1oM47C6+bik9sx7?=
 =?us-ascii?Q?eEPGGee8tigTS7mKqUN62EczAZR6VsVTmNQB6m8ddQKJzTGPVpONsFe/ENar?=
 =?us-ascii?Q?7xhLswxzKpIa8mT+ddqQVZYQr4yz0evV0ezNgE/xmyHSebfilclijSKdlGaj?=
 =?us-ascii?Q?mVCfpApCX2vVtklrIhcCX9H5GYEW9O81VMMAwLDJU/uiBvB01WewWm3yN8/M?=
 =?us-ascii?Q?GunEDWaRs5Q6G7o/Y8AosnoIQyVZzPCUGJeFQNNP2M/VXFnHtFwbXqSSwMWF?=
 =?us-ascii?Q?jcbHJoJIoISiPH6NcWa3TCDtnLFL/3TbQsO5pISH3sT8+hGeqdM4QYJxMQdZ?=
 =?us-ascii?Q?sZUwI4lnE56jDEMZHjhXUiPR05bkM9VvoUFYxTtk10FjXtH9oJQsZWi87I0+?=
 =?us-ascii?Q?sorLL/kvCaeTJ2X/RSwD+tJh6m5H1AmHHWUR3EjQiR0ylg2/EdMOQS6nS9wl?=
 =?us-ascii?Q?I+QeLiE4ppxnbprUU8z0ILKioA1V5SRiv4d/I8tbty59YvZ4UTEO13iMuUM+?=
 =?us-ascii?Q?gvj68V6WWneMoSCpXaPBiCc9GwYM3kVCwOlhM+kIhAn4g71flxrqQXfwV29C?=
 =?us-ascii?Q?F+y14H9bkeiaZoZOnPrXRHxkZNV2L2dKXTN5v5sehYznzNf7ZoWYS5sqWFbx?=
 =?us-ascii?Q?FhF3fh//WqZs2dMIosjc9X9J2rPD7l2997WnnzB0/YWID+YER/CYNXLrl0yt?=
 =?us-ascii?Q?/PQ1V0/vM1RxlsOdzxgo8AsSHAneSosRjZXfR1F04urW2P2WvSafqLzA+nBe?=
 =?us-ascii?Q?5qPRZm/rFOKEhO1VdA4zImukq4q3Ga6dFSZXAdJqY0rpcMI1e9BPkkz/QZJN?=
 =?us-ascii?Q?L0rnzlIFzZbVvl4gKHwClpHhESqhRw+6M5cCqSs9zB7Ezo436+Hd0erwky6k?=
 =?us-ascii?Q?bgLTyuZ9ZqTVa0MJjNpI+di+31sBLT5k0FL7dn0Ejy8KFrQxlZg/6Vpzk/X0?=
 =?us-ascii?Q?mu2fHYa4alX7tgxWu8Ly1HtOsgQhzWS4v4kQKt7IouGWQmttWHhH0DFifssK?=
 =?us-ascii?Q?unI5ItdxIt9tc0eF9NIvMW/gsS7Efyt4ErsaDH/GGQDt1MxfpCxjxTOXztSW?=
 =?us-ascii?Q?Krh1zMTLwX5QzDsDVZk3OjjTNmYS8EpQZu7li/oE5kiqUjC4ry4rUqT2TWix?=
 =?us-ascii?Q?g9o9N/APrlurn2jkG9/spM0OBEkSvMuc1JboLw37RPbTHk3tM3zwAOrFjhdx?=
 =?us-ascii?Q?AXzF0vGgWNKUrLdKAr1KTGP3kZAgYWC9RWsz/2uf9zg6p9AFonmKYBR9P2cF?=
 =?us-ascii?Q?NC83okdrSuJTHtuFX2SCnhT4W4FrwkY8OMOOuLbqs4gzPy7WHCPHDAHOKLiS?=
 =?us-ascii?Q?DmUqtiOfU2EY8Yb5Vi1FbWcuT95UkzwClY/sG8XsbbHJCkHTUTpkmRcFxEZn?=
 =?us-ascii?Q?ZVz8l1YN5Cy1YZrAIqkzHtztpwXXOCLhA9avvFTBNnzBw+KJrNdTVus+kR8F?=
 =?us-ascii?Q?CnqlDKR2rYKgNXuoDFgbtYQJAGzqD0nxuRXRqWwdszVM4c+eEEyMbO6l2p31?=
 =?us-ascii?Q?lErmVdz99CJ2zeX61I86UZbpyUh3nIFIkDJJsz5lYo+8McNj4O/t1Oh60VKL?=
 =?us-ascii?Q?MYMTLxHO0eFawNqVeB9/RWz5GhzrEN+QCOwbA/dvmdK89DP4ljOS6/IwtFyr?=
 =?us-ascii?Q?thSkXQ=3D=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-OriginatorOrg: renesas.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: TYBPR01MB5341.jpnprd01.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: f92b574b-571f-4891-2240-08dabe1d3207
X-MS-Exchange-CrossTenant-originalarrivaltime: 04 Nov 2022 04:29:42.8378
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 53d82571-da19-47e4-9cb4-625a166a4a2a
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: X1IFrSBZdrrSdClkhFEeJNUTZbhBG/aunvUyIdxs9AiL9xdboTGJMy+7+GfSSRi2LuLhYyrtI0RWPOj4rL17NERpXSDa4dETVRmFMqOwdGVVvwCtBRSq7bL9cPqKKfVC
X-MS-Exchange-Transport-CrossTenantHeadersStamped: TY3PR01MB9746
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi, Nathan,

> From: Nathan Chancellor, Sent: Friday, November 4, 2022 7:01 AM
>=20
> With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
> indirect call targets are validated against the expected function
> pointer prototype to make sure the call target is valid to help mitigate
> ROP attacks. If they are not identical, there is a failure at run time,
> which manifests as either a kernel panic or thread getting killed. A
> proposed warning in clang aims to catch these at compile time, which
> reveals:
>=20
>   drivers/net/ethernet/renesas/rswitch.c:1533:20: error: incompatible fun=
ction pointer types initializing 'netdev_tx_t
> (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(stru=
ct sk_buff *, struct net_device *)') with an
> expression of type 'int (struct sk_buff *, struct net_device *)' [-Werror=
,-Wincompatible-function-pointer-types-strict]
>           .ndo_start_xmit =3D rswitch_start_xmit,
>                           ^~~~~~~~~~~~~~~~~~
>   1 error generated.
>=20
> ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of
> 'netdev_tx_t', not 'int'. Adjust the return type of rswitch_start_xmit()
> to match the prototype's to resolve the warning and CFI failure.
>=20
> Link: https://github.com/ClangBuiltLinux/linux/issues/1750
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---

Thank you for the patch!

Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

Best regards,
Yoshihiro Shimoda

>  drivers/net/ethernet/renesas/rswitch.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/etherne=
t/renesas/rswitch.c
> index 20df2020d3e5..f0168fedfef9 100644
> --- a/drivers/net/ethernet/renesas/rswitch.c
> +++ b/drivers/net/ethernet/renesas/rswitch.c
> @@ -1390,7 +1390,7 @@ static int rswitch_stop(struct net_device *ndev)
>  	return 0;
>  };
>=20
> -static int rswitch_start_xmit(struct sk_buff *skb, struct net_device *nd=
ev)
> +static netdev_tx_t rswitch_start_xmit(struct sk_buff *skb, struct net_de=
vice *ndev)
>  {
>  	struct rswitch_device *rdev =3D netdev_priv(ndev);
>  	struct rswitch_gwca_queue *gq =3D rdev->tx_queue;
>=20
> base-commit: ef2dd61af7366e5a42e828fff04932e32eb0eacc
> --
> 2.38.1