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,USER_AGENT_SANE_1 autolearn=ham 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 83210C3F2D2 for ; Sat, 29 Feb 2020 00:08:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54345246AE for ; Sat, 29 Feb 2020 00:08:12 +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="tRctQ/gt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726621AbgB2AIK (ORCPT ); Fri, 28 Feb 2020 19:08:10 -0500 Received: from gateway33.websitewelcome.com ([192.185.145.221]:29960 "EHLO gateway33.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726359AbgB2AIJ (ORCPT ); Fri, 28 Feb 2020 19:08:09 -0500 Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway33.websitewelcome.com (Postfix) with ESMTP id 264E8187B7C for ; Fri, 28 Feb 2020 18:08:08 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 7pfsjcbTbAGTX7pfsjlT27; Fri, 28 Feb 2020 18:08:08 -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=zfaaTppUw/YMS2SHvO7uOLQjxhi/2WNpD6bDMsCd+WU=; b=tRctQ/gtfM+yfdtCBct6yCTOYK p4IaMOXmC3ve32NhJZ5OGIAXtY8Du6SqDiPoCaO4MCsPxCjqHlSQvLq2KxkRQoQP7NfzbzBU16C/Y LSkGzGx3gnCbAqLJ3X/S9Yh7v0H0XGES3WKVDY2VpDvBKiGY0OBU1d011I79L2AfWqG3GiQW/Rzhr D6UtIcV+E1Y5hWpJZsVy8DgmvLns4z5o1fbt76O/pju18PsjbrxGm33lTdYUXFzxHAQeIqDW7JaiE QAV+pIbY/BOMnWHW1mbtPy6420c3fGB9Hgy2VwOUyfO/45hX69U1X0LB+rDK6jnyjvsMHPfJ2eSZw F0MRS4hw==; Received: from [200.39.15.57] (port=9598 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j7pfq-002cpS-Bo; Fri, 28 Feb 2020 18:08:06 -0600 Date: Fri, 28 Feb 2020 18:11:02 -0600 From: "Gustavo A. R. Silva" To: "David S. Miller" , Jakub Kicinski Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] net: sock_reuseport: Replace zero-length array with flexible-array member Message-ID: <20200229001102.GA6418@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: 200.39.15.57 X-Source-L: No X-Exim-ID: 1j7pfq-002cpS-Bo X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.39.15.57]:9598 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 3 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/net/sock_reuseport.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/net/sock_reuseport.h b/include/net/sock_reuseport.h index 3ecaa15d1850..505f1e18e9bf 100644 --- a/include/net/sock_reuseport.h +++ b/include/net/sock_reuseport.h @@ -24,7 +24,7 @@ struct sock_reuseport { unsigned int bind_inany:1; unsigned int has_conns:1; struct bpf_prog __rcu *prog; /* optional BPF sock selector */ - struct sock *socks[0]; /* array of sock pointers */ + struct sock *socks[]; /* array of sock pointers */ }; extern int reuseport_alloc(struct sock *sk, bool bind_inany); -- 2.25.0