From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F33C7C4332F for ; Sun, 18 Dec 2022 16:25:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232064AbiLRQZu (ORCPT ); Sun, 18 Dec 2022 11:25:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231933AbiLRQYc (ORCPT ); Sun, 18 Dec 2022 11:24:32 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B4446DEC1; Sun, 18 Dec 2022 08:09:46 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 29F4760C58; Sun, 18 Dec 2022 16:09:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2E396C433D2; Sun, 18 Dec 2022 16:09:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671379773; bh=bylQ92nndUsQDEdsR7BlnEBaPmFt2kKNmE0KssvA6Mg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TX6qtBg19uForBAZ0Zcm1Ox9qUNLrZtRirIZbsKdCMq8ANTX5/Ses6ut1b+HDninP umyGoI/ux8COYFHOfLcjhE7puWasPFteF3/zMFAAGfyX2wMWchaembrAPadlgV/EoI 1aQ0RsbH6yIu+4D7gJ74LZOc+rn2qqd03tLRWKBaiBYJzO7UevLvBOEs5EglseWys9 vwxb8rq3qpWh3boUAsy3Wt0PWVnmzyG+plvEaXEYnSj8f8BhEqy0dyoc7ChiE7YlFz Iw9WpwreKWweixWr1wviij7M3aA2pS77D23azQTOSaNRIKahsC6Ui5eRpEUwjIL7Yy 6dIZ/qM+F29cQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Nathan Chancellor , Alexandra Winter , Kees Cook , "David S . Miller" , Sasha Levin , wenjia@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, ndesaulniers@google.com, linux-s390@vger.kernel.org, netdev@vger.kernel.org, llvm@lists.linux.dev Subject: [PATCH AUTOSEL 6.0 30/73] s390/lcs: Fix return type of lcs_start_xmit() Date: Sun, 18 Dec 2022 11:06:58 -0500 Message-Id: <20221218160741.927862-30-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221218160741.927862-1-sashal@kernel.org> References: <20221218160741.927862-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Nathan Chancellor [ Upstream commit bb16db8393658e0978c3f0d30ae069e878264fa3 ] 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/s390/net/lcs.c:2090:21: 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 = lcs_start_xmit, ^~~~~~~~~~~~~~ drivers/s390/net/lcs.c:2097:21: 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 = lcs_start_xmit, ^~~~~~~~~~~~~~ ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of 'netdev_tx_t', not 'int'. Adjust the return type of lcs_start_xmit() to match the prototype's to resolve the warning and potential CFI failure, should s390 select ARCH_SUPPORTS_CFI_CLANG in the future. Link: https://github.com/ClangBuiltLinux/linux/issues/1750 Reviewed-by: Alexandra Winter Reviewed-by: Kees Cook Signed-off-by: Nathan Chancellor Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/s390/net/lcs.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/s390/net/lcs.c b/drivers/s390/net/lcs.c index 84c8981317b4..38f312664ce7 100644 --- a/drivers/s390/net/lcs.c +++ b/drivers/s390/net/lcs.c @@ -1519,9 +1519,8 @@ lcs_txbuffer_cb(struct lcs_channel *channel, struct lcs_buffer *buffer) /* * Packet transmit function called by network stack */ -static int -__lcs_start_xmit(struct lcs_card *card, struct sk_buff *skb, - struct net_device *dev) +static netdev_tx_t __lcs_start_xmit(struct lcs_card *card, struct sk_buff *skb, + struct net_device *dev) { struct lcs_header *header; int rc = NETDEV_TX_OK; @@ -1582,8 +1581,7 @@ __lcs_start_xmit(struct lcs_card *card, struct sk_buff *skb, return rc; } -static int -lcs_start_xmit(struct sk_buff *skb, struct net_device *dev) +static netdev_tx_t lcs_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct lcs_card *card; int rc; -- 2.35.1