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=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 A5D82C3F2D2 for ; Fri, 28 Feb 2020 13:40:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A70A246AE for ; Fri, 28 Feb 2020 13:40:33 +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="g+4fKStd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726758AbgB1Nkc (ORCPT ); Fri, 28 Feb 2020 08:40:32 -0500 Received: from gateway24.websitewelcome.com ([192.185.51.202]:47297 "EHLO gateway24.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726418AbgB1Nkb (ORCPT ); Fri, 28 Feb 2020 08:40:31 -0500 Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway24.websitewelcome.com (Postfix) with ESMTP id CDEC881617 for ; Fri, 28 Feb 2020 07:40:30 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 7fsUjuKxKSl8q7fsUjYLBB; Fri, 28 Feb 2020 07:40:30 -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=vo0s0HHcKUWbR9UQkp85XxEyo8pNBh5ee/gMXGBhILo=; b=g+4fKStdx4DsG5MhPZ1ImJeoAQ nxPmXBYvHhSIK6R/+xXj0oX1FMiZfo/8iRMYOfx1Nws8/MH57qvSkWs0ChCYz09LkM7cYM39s4oYO ub7PMz8jrFSTYz8JvlwmwkEIcLCdW7WeOuTzZRwc4EnSDb8gtc0LL6Y8YC5N+VntqTofnMKWQ9M83 rFgslmPY1Qwp3b677NVkxUmvRelrCatITwxdyCqoGIUXGbTSJL3lOdU2IvUXNIxWIXbRTHUzIwekO 0uWpJfGWeT0Rh3fEVHLkPFvTX5kOoL4qcH8P7zZy7PsJXwlCCH76ILHktJHSxyyPJ2XJSZuNUEXpQ gEwkk7YA==; Received: from [201.162.240.44] (port=19035 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j7fsS-001RcU-L0; Fri, 28 Feb 2020 07:40:29 -0600 Date: Fri, 28 Feb 2020 07:43:24 -0600 From: "Gustavo A. R. Silva" To: "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , Jiri Pirko , Neil Horman Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] net: core: Replace zero-length array with flexible-array member Message-ID: <20200228134324.GA29394@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: 1j7fsS-001RcU-L0 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.240.44]:19035 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 53 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 --- net/core/bpf_sk_storage.c | 2 +- net/core/devlink.c | 2 +- net/core/drop_monitor.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index 3ab23f698221..427cfbc0d50d 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -60,7 +60,7 @@ struct bpf_sk_storage_data { * the number of cachelines access during the cache hit case. */ struct bpf_sk_storage_map __rcu *smap; - u8 data[0] __aligned(8); + u8 data[] __aligned(8); }; /* Linked to bpf_sk_storage and bpf_sk_storage_map */ diff --git a/net/core/devlink.c b/net/core/devlink.c index f8af5e2d748b..295d761cbfb1 100644 --- a/net/core/devlink.c +++ b/net/core/devlink.c @@ -4232,7 +4232,7 @@ struct devlink_fmsg_item { int attrtype; u8 nla_type; u16 len; - int value[0]; + int value[]; }; struct devlink_fmsg { diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c index d58c1c45a895..8e33cec9fc4e 100644 --- a/net/core/drop_monitor.c +++ b/net/core/drop_monitor.c @@ -68,7 +68,7 @@ struct net_dm_hw_entry { struct net_dm_hw_entries { u32 num_entries; - struct net_dm_hw_entry entries[0]; + struct net_dm_hw_entry entries[]; }; struct per_cpu_dm_data { -- 2.25.0