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 9822BC54EBE for ; Mon, 16 Jan 2023 16:38:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233590AbjAPQiA (ORCPT ); Mon, 16 Jan 2023 11:38:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233552AbjAPQhZ (ORCPT ); Mon, 16 Jan 2023 11:37:25 -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 1979D2310B for ; Mon, 16 Jan 2023 08:26:20 -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 8D5AE6105C for ; Mon, 16 Jan 2023 16:26:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A2B8EC433D2; Mon, 16 Jan 2023 16:26:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673886380; bh=kiFGMI3/XTbP6ilHB9Cd0kQN0nS+WVOU7gHezoV3SnA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kq7LIEIEgPIThSWXjitHDORFQ1CyTbBbMst12IFeUwZ2SHXN++yYjOYXU5brze0ab l+gcXQefBfhFm5bgrqsJA/BUI5Tdz3L2kThbp5IXwNRRTB4zqAvYvceq1CH0FzfBUG Hyd9dvkNVnNxq/Hajmv23OSTMcH7tWcIAN/GNIkI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alexandra Winter , Kees Cook , Nathan Chancellor , "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 408/658] s390/lcs: Fix return type of lcs_start_xmit() Date: Mon, 16 Jan 2023 16:48:16 +0100 Message-Id: <20230116154928.264778568@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230116154909.645460653@linuxfoundation.org> References: <20230116154909.645460653@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@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 4eec7bfb5de9..73708166b255 100644 --- a/drivers/s390/net/lcs.c +++ b/drivers/s390/net/lcs.c @@ -1518,9 +1518,8 @@ 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; @@ -1581,8 +1580,7 @@ __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