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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Sergey Shtylyov , Yoshihiro Shimoda , netdev@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Nick Desaulniers , Tom Rix , Kees Cook , Sami Tolvanen , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Nathan Chancellor Subject: [PATCH net-next] net: ethernet: renesas: Fix return type of rswitch_start_xmit() Date: Thu, 3 Nov 2022 15:00:32 -0700 Message-Id: <20221103220032.2142122-1-nathan@kernel.org> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 X-Spam-Status: No, score=-8.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,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: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1748514128539701873?= X-GMAIL-MSGID: =?utf-8?q?1748514128539701873?= 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: drivers/net/ethernet/renesas/rswitch.c:1533:20: error: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct 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 = rswitch_start_xmit, ^~~~~~~~~~~~~~~~~~ 1 error generated. ->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. Link: https://github.com/ClangBuiltLinux/linux/issues/1750 Signed-off-by: Nathan Chancellor Reviewed-by: Yoshihiro Shimoda Reviewed-by: Kees Cook --- drivers/net/ethernet/renesas/rswitch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) base-commit: ef2dd61af7366e5a42e828fff04932e32eb0eacc diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/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; }; -static int rswitch_start_xmit(struct sk_buff *skb, struct net_device *ndev) +static netdev_tx_t rswitch_start_xmit(struct sk_buff *skb, struct net_device *ndev) { struct rswitch_device *rdev = netdev_priv(ndev); struct rswitch_gwca_queue *gq = rdev->tx_queue;