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 X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12938C3F2D2 for ; Fri, 28 Feb 2020 13:36:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB18224680 for ; Fri, 28 Feb 2020 13:36:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=embeddedor.com header.i=@embeddedor.com header.b="ZSBryY7s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726733AbgB1NgV (ORCPT ); Fri, 28 Feb 2020 08:36:21 -0500 Received: from gateway32.websitewelcome.com ([192.185.144.98]:39047 "EHLO gateway32.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726151AbgB1NgU (ORCPT ); Fri, 28 Feb 2020 08:36:20 -0500 X-Greylist: delayed 366 seconds by postgrey-1.27 at vger.kernel.org; Fri, 28 Feb 2020 08:36:20 EST Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway32.websitewelcome.com (Postfix) with ESMTP id 0452B1A2BB for ; Fri, 28 Feb 2020 07:30:44 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 7fj1jCUij8vkB7fj1j7Goa; Fri, 28 Feb 2020 07:30:44 -0600 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=embeddedor.com; s=default; h=Content-Type:MIME-Version:Message-ID:Subject: Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=Lu2UNNDEeNiF01lLdVnT5hMzc2S6yAIGWedaWMTmuQY=; b=ZSBryY7s+UYvF2h7EmzUfUGGpi kkz4X1ZLl+3mp2mk9lDTwGX65cXpHnsQhZ2EcB3P8Z/D54g7jJG2nr3QHB7tA4jXWJbBQ0QBxeDwf td+c/BkT3XeCR0T1djdkEW4i9iUL4dcK4Fw0/pNnf4SS14Q7/6kBp666BJh400eWmZP7TO5O6uT3/ VxFZ2ug1JFD+u6KhwirQsDfLIrsI4vG+Df9EF6hswflK0CORs8wY5F2krITiFRgy3yrM+sxeBDsrS EkZmGzxB8hEaktOoZPEF1invSKxbjrb5cHfpiu85L/4xq2hCY9MSpicokh1bbapMwETkH99A+mSVI gFPCmWGA==; Received: from [201.162.240.44] (port=16592 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j7fiz-001MVV-WD; Fri, 28 Feb 2020 07:30:42 -0600 Date: Fri, 28 Feb 2020 07:33:37 -0600 From: "Gustavo A. R. Silva" To: Gerrit Renker , "David S. Miller" , Jakub Kicinski Cc: dccp@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] net: dccp: Replace zero-length array with flexible-array member Message-ID: <20200228133337.GA23619@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 201.162.240.44 X-Source-L: No X-Exim-ID: 1j7fiz-001MVV-WD X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.240.44]:16592 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 32 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva --- include/linux/dccp.h | 2 +- net/dccp/ccid.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/dccp.h b/include/linux/dccp.h index 6b64b6cc2175..07e547c02fd8 100644 --- a/include/linux/dccp.h +++ b/include/linux/dccp.h @@ -198,7 +198,7 @@ enum dccp_role { struct dccp_service_list { __u32 dccpsl_nr; - __be32 dccpsl_list[0]; + __be32 dccpsl_list[]; }; #define DCCP_SERVICE_INVALID_VALUE htonl((__u32)-1) diff --git a/net/dccp/ccid.h b/net/dccp/ccid.h index 70f88f2b4456..105f3734dadb 100644 --- a/net/dccp/ccid.h +++ b/net/dccp/ccid.h @@ -95,7 +95,7 @@ void ccid_cleanup_builtins(void); struct ccid { struct ccid_operations *ccid_ops; - char ccid_priv[0]; + char ccid_priv[]; }; static inline void *ccid_priv(const struct ccid *ccid) -- 2.25.0