From patchwork Sat Feb 29 01:02:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 1246942 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=embeddedor.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=embeddedor.com header.i=@embeddedor.com header.a=rsa-sha256 header.s=default header.b=TsGPF8Ib; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48Tp3P2xpbz9sRJ for ; Sat, 29 Feb 2020 12:00:01 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726783AbgB2BAA (ORCPT ); Fri, 28 Feb 2020 20:00:00 -0500 Received: from gateway22.websitewelcome.com ([192.185.47.163]:20111 "EHLO gateway22.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726418AbgB2BAA (ORCPT ); Fri, 28 Feb 2020 20:00:00 -0500 Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway22.websitewelcome.com (Postfix) with ESMTP id 57E54B4D65 for ; Fri, 28 Feb 2020 18:59:59 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 7qU3jdMVXAGTX7qU3jmDi7; Fri, 28 Feb 2020 18:59:59 -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=09qBJCuV/qfG9uVAPQck4bm+6ufBYKRI0cgJkKY3QlE=; b=TsGPF8Ib7thdSZ5hUAKHUjEtl1 7G/Y+oqHWJBnFwf7tiD7GazelZ/06uaJjjdPxiNCQWF0mab4VIWCrDaG2YMuJcDkZewT2CoQwRZRA Y7k5RQOLAru1+DyYYfYWW8kQoEGOAX4VhT2FmVQFWSJaZtwD5I261dwJ8PWDOrq8GyhJ+VTBc4Vsr 7Ig0jxIRUNkdESYJ6ej/VU2nBUyRg/8Ke3TfFGQld1ZgBhYiVFdc69Qo+vkbZZWhQVefhnooDfsel OFO+RVFGV1+scG3Vo8G4rG8i8wjI9s+cMQ2kNnfVdr728IwYeFJLJly8YQl3uPbNAXFj2FuScIR5Z wcJV1Ajg==; Received: from [200.39.15.57] (port=20013 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j7qU1-002yoq-Gw; Fri, 28 Feb 2020 18:59:57 -0600 Date: Fri, 28 Feb 2020 19:02:54 -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: flow_offload: Replace zero-length array with flexible-array member Message-ID: <20200229010254.GA9547@embeddedor> MIME-Version: 1.0 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: 1j7qU1-002yoq-Gw X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [200.39.15.57]:20013 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 42 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/flow_offload.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h index 4e864c34a1b0..cd3510ac66b0 100644 --- a/include/net/flow_offload.h +++ b/include/net/flow_offload.h @@ -229,7 +229,7 @@ struct flow_action_entry { struct flow_action { unsigned int num_entries; - struct flow_action_entry entries[0]; + struct flow_action_entry entries[]; }; static inline bool flow_action_has_entries(const struct flow_action *action)