From patchwork Wed Feb 26 21:23:17 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: 1245341 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=hWN5RsL2; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48STH43sbrz9sPK for ; Thu, 27 Feb 2020 08:20:32 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727576AbgBZVUa (ORCPT ); Wed, 26 Feb 2020 16:20:30 -0500 Received: from gateway30.websitewelcome.com ([192.185.196.18]:21971 "EHLO gateway30.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727486AbgBZVU3 (ORCPT ); Wed, 26 Feb 2020 16:20:29 -0500 Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway30.websitewelcome.com (Postfix) with ESMTP id E30CE36EB for ; Wed, 26 Feb 2020 15:20:27 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 746VjFuQEXVkQ746Vjb7hG; Wed, 26 Feb 2020 15:20:27 -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=u27AWESU6IBnunkwxt/DOyNrqsBFUtPolFnlbLmyax0=; b=hWN5RsL2079aQWubVBv8qBN4wE eW+GIP42AvfEqYGxZj4MaTWSYHq+AaLEcwe5WZQOs451KliadxqfypJUZOhVYIiti6Ux4Y2FBIPDS wRBfndyWfD2WJWZu4VsEK3Ib6LWmjtsCqC/bYjLBTsd48qdnrERuT48kqMvMQd5MnHQoqeLT1KF7T vZXNHdICj2VdH/zn6DSS0//BcwoXfs0tvIxCv7VkZ6/xvKUhr3CS8N7Zbk0oMZQhvIVDVF46k336C W0twgwTyeQ0cxyVgpk87sUua6UJJplRxMB/Cv5COLxRbxJW9TgIeg1eGvLlhcgM7MY9vktzWLYrWw u+Dwikhg==; Received: from [201.162.161.146] (port=47662 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j746T-000m4L-0m; Wed, 26 Feb 2020 15:20:25 -0600 Date: Wed, 26 Feb 2020 15:23:17 -0600 From: "Gustavo A. R. Silva" To: Kevin Curtis , "David S. Miller" , Krzysztof Halasa Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] WAN: Replace zero-length array with flexible-array member Message-ID: <20200226212317.GA2172@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: 201.162.161.146 X-Source-L: No X-Exim-ID: 1j746T-000m4L-0m X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.161.146]:47662 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 15 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 --- drivers/net/wan/farsync.h | 2 +- drivers/net/wan/wanxl.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/wan/farsync.h b/drivers/net/wan/farsync.h index 47b8e36f97ab..5f43568a9715 100644 --- a/drivers/net/wan/farsync.h +++ b/drivers/net/wan/farsync.h @@ -65,7 +65,7 @@ struct fstioc_write { unsigned int size; unsigned int offset; - unsigned char data[0]; + unsigned char data[]; }; diff --git a/drivers/net/wan/wanxl.c b/drivers/net/wan/wanxl.c index 23f93f1c815d..499f7cd19a4a 100644 --- a/drivers/net/wan/wanxl.c +++ b/drivers/net/wan/wanxl.c @@ -78,7 +78,7 @@ struct card { struct sk_buff *rx_skbs[RX_QUEUE_LENGTH]; struct card_status *status; /* shared between host and card */ dma_addr_t status_address; - struct port ports[0]; /* 1 - 4 port structures follow */ + struct port ports[]; /* 1 - 4 port structures follow */ };