From patchwork Thu Mar 5 11:06:44 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: 11421569 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 92ABC14BC for ; Thu, 5 Mar 2020 11:23:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 733DA208CD for ; Thu, 5 Mar 2020 11:23:53 +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="bKp6mtkg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726049AbgCELXx (ORCPT ); Thu, 5 Mar 2020 06:23:53 -0500 Received: from gateway33.websitewelcome.com ([192.185.145.190]:25739 "EHLO gateway33.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725880AbgCELXx (ORCPT ); Thu, 5 Mar 2020 06:23:53 -0500 X-Greylist: delayed 1212 seconds by postgrey-1.27 at vger.kernel.org; Thu, 05 Mar 2020 06:23:52 EST Received: from cm11.websitewelcome.com (cm11.websitewelcome.com [100.42.49.5]) by gateway33.websitewelcome.com (Postfix) with ESMTP id AE45223E39 for ; Thu, 5 Mar 2020 05:03:40 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 9oI0jQ6fWSl8q9oI0j2ZRU; Thu, 05 Mar 2020 05:03:40 -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=AKyS/FSSKOcktqfRdmBIG2IkRBKAyZrf6dcf3eo+zjY=; b=bKp6mtkgJEuAkukD00EYIF48Rx mieJyYDNSDAzAP/A0l8ZE+HjCkLGj6fWmKc82C9MN4jy57+ZwR1xOv3g5mMPO3889iBE29//9yUPh lMwDbqkjN6BCDRaM/wwyx8rAt4J/KVXxmbB6tMXwMEhP1045AS7mbpTK8V3+wX56qPc16ADsLC9pE tldiSA36SXYx8bR86PYzY7YNzWfMPdhFaC+ERz8MULe9lRebA9teFSqnW/YVGlzPU662zhau5UF3H VttR5po0oLB7MBbeCrbmsylIviT0SpAWXrvMRk5TriWzKqNFmS2zmMjmWZ9RTvdoj2DlE50YuU5av bB3KkAFg==; Received: from [201.166.169.220] (port=7940 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j9oHy-003n2K-UE; Thu, 05 Mar 2020 05:03:39 -0600 Date: Thu, 5 Mar 2020 05:06:44 -0600 From: "Gustavo A. R. Silva" To: "David S. Miller" Cc: netdev@vger.kernel.org, linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] net: tulip: Replace zero-length array with flexible-array member Message-ID: <20200305110644.GA8604@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: 201.166.169.220 X-Source-L: No X-Exim-ID: 1j9oHy-003n2K-UE X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.166.169.220]:7940 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 3 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@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/ethernet/dec/tulip/tulip.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/dec/tulip/tulip.h b/drivers/net/ethernet/dec/tulip/tulip.h index b458140aeaef..815907259048 100644 --- a/drivers/net/ethernet/dec/tulip/tulip.h +++ b/drivers/net/ethernet/dec/tulip/tulip.h @@ -381,7 +381,7 @@ struct mediatable { unsigned has_reset:6; u32 csr15dir; u32 csr15val; /* 21143 NWay setting. */ - struct medialeaf mleaf[0]; + struct medialeaf mleaf[]; };