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 4186FC10F1E for ; Sun, 18 Dec 2022 17:11:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233640AbiLRRLQ (ORCPT ); Sun, 18 Dec 2022 12:11:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233556AbiLRRJW (ORCPT ); Sun, 18 Dec 2022 12:09:22 -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 672CC1E739; Sun, 18 Dec 2022 08:23:30 -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 06A2960D39; Sun, 18 Dec 2022 16:23:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0178CC433F2; Sun, 18 Dec 2022 16:23:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671380609; bh=+00UY4f7a5DPfcKQN9KRu4BLT5iLBbH0X5OnmpuZ12A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pT5xTu9Tb+4JV0C05CP3gsg+4FotNOa2qhOzw2zUEiTanr9XgxpZF5X0ZG91f7DSd zL0AC52JGgY4rQoVKgC+PIBILy31OJQyRqetHazUn5SGn9pW91KdEpjp6nj1C9D4Kb stLPTh/Wr6cHosfGbhTBz0hgy58C3LKOWS/gSRC2dY+Kd71/0O1GK9wgriOl6rwr8i ZoCu4Boyc0TsGjRwMjUQh5n/92/eTDM8tB45rL4ZzFZToxrvAaP09YvrAlDJfW3r9i FkPSu6KMT1AZfaVldZmkdR8hjm7yXHsRJOQlXY55sqcMAqRom7zosIArtBsJ4aaiAA /EunN1icLXdiA== 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 4.9 08/20] s390/ctcm: Fix return type of ctc{mp,}m_tx() Date: Sun, 18 Dec 2022 11:22:53 -0500 Message-Id: <20221218162305.935724-8-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221218162305.935724-1-sashal@kernel.org> References: <20221218162305.935724-1-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 aa5bf80c3c067b82b4362cd6e8e2194623bcaca6 ] 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/ctcm_main.c:1064:21: 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 = ctcm_tx, ^~~~~~~ drivers/s390/net/ctcm_main.c:1072:21: 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 = ctcmpc_tx, ^~~~~~~~~ ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of 'netdev_tx_t', not 'int'. Adjust the return type of ctc{mp,}m_tx() to match the prototype's to resolve the warning and potential CFI failure, should s390 select ARCH_SUPPORTS_CFI_CLANG in the future. Additionally, while in the area, remove a comment block that is no longer relevant. 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/ctcm_main.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c index e22b9ac3e564..ab48eef72d4f 100644 --- a/drivers/s390/net/ctcm_main.c +++ b/drivers/s390/net/ctcm_main.c @@ -866,16 +866,9 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb) /** * Start transmission of a packet. * Called from generic network device layer. - * - * skb Pointer to buffer containing the packet. - * dev Pointer to interface struct. - * - * returns 0 if packet consumed, !0 if packet rejected. - * Note: If we return !0, then the packet is free'd by - * the generic network layer. */ /* first merge version - leaving both functions separated */ -static int ctcm_tx(struct sk_buff *skb, struct net_device *dev) +static netdev_tx_t ctcm_tx(struct sk_buff *skb, struct net_device *dev) { struct ctcm_priv *priv = dev->ml_priv; @@ -918,7 +911,7 @@ static int ctcm_tx(struct sk_buff *skb, struct net_device *dev) } /* unmerged MPC variant of ctcm_tx */ -static int ctcmpc_tx(struct sk_buff *skb, struct net_device *dev) +static netdev_tx_t ctcmpc_tx(struct sk_buff *skb, struct net_device *dev) { int len = 0; struct ctcm_priv *priv = dev->ml_priv; -- 2.35.1