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 C7B30C4332F for ; Sun, 18 Dec 2022 16:06:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231490AbiLRQGx (ORCPT ); Sun, 18 Dec 2022 11:06:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33906 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231229AbiLRQFE (ORCPT ); Sun, 18 Dec 2022 11:05:04 -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 306FDBC3A; Sun, 18 Dec 2022 08:04:00 -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 C408360DD0; Sun, 18 Dec 2022 16:03:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B602EC433F2; Sun, 18 Dec 2022 16:03:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671379439; bh=bylQ92nndUsQDEdsR7BlnEBaPmFt2kKNmE0KssvA6Mg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W879Ik9HK//as7oTUsQ7YuQEK2NItpfNAQJ4FzJXn736VZEtuwek0XZNzz7D20eNV SWmkHICuKvjXieAu0J1ooNVQ2kVBEL8tI0EroiQ3ZaDwOKK1F7IFYSTN7uEtdD5cT/ m76bso0Yl72nfZ5cdsZ2Vhsuc8CnCxyfgvIL4nV3m9kMhPmlBF3CQkS1M/lHYfPY9W YXmHeQt/YCqXyuZSzT9xEDGGlrhYi0leTsBCPUsWOuVg86lNKmPQFGYqYescKUBBDt oioXlfRTiwWiTLvxj2Ld0WDB6EaaGJBJizWul7DvD9/1sCgmVjArBsJziROe3RoeZB xAsNzLcUqhixQ== 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 6.1 35/85] s390/lcs: Fix return type of lcs_start_xmit() Date: Sun, 18 Dec 2022 11:00:52 -0500 Message-Id: <20221218160142.925394-35-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221218160142.925394-1-sashal@kernel.org> References: <20221218160142.925394-1-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