From patchwork Fri Feb 28 13:23:23 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: 11412283 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 81A5B138D for ; Fri, 28 Feb 2020 13:44:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60A0B2072A for ; Fri, 28 Feb 2020 13:44:33 +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="Q3cFP3w1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726378AbgB1Noc (ORCPT ); Fri, 28 Feb 2020 08:44:32 -0500 Received: from gateway33.websitewelcome.com ([192.185.145.33]:46861 "EHLO gateway33.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726151AbgB1Noc (ORCPT ); Fri, 28 Feb 2020 08:44:32 -0500 X-Greylist: delayed 1441 seconds by postgrey-1.27 at vger.kernel.org; Fri, 28 Feb 2020 08:44:31 EST Received: from cm13.websitewelcome.com (cm13.websitewelcome.com [100.42.49.6]) by gateway33.websitewelcome.com (Postfix) with ESMTP id 2F4C92ED332 for ; Fri, 28 Feb 2020 07:20:30 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 7fZ8jI9I6RP4z7fZ8jgYWM; Fri, 28 Feb 2020 07:20:30 -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=vHClNfI7Qt5b0uR7/2n+CnDKDelWTosbitfxyh2nN0A=; b=Q3cFP3w1ZSCtsPw8tSf3hEQPhI o4fh9MiD6FQJUJlfdY0vG3LSu7+32VHQB/fz/w5bxSB/8C09WWZfH21gVePxit9L5Usf28+Y5bGEZ lMO1R2VnPt5qIJXvuqCTMRUx0ADwvdUY3CMMTX9CuVHdSNFLYQZRMuzWgdCEg9VbBVIySUMOazeNa YxakP40SINiiWOkq7FzX14iMlwxp0lpnrnbdreiV85ox/wUzyv4QL7yyr3UXkLevaB2jICeseKwtT ZmUw+KK7iAuDFJHVut86Dx/ATtXag5JC+2PG6yWy6OOlRNk1oN6sCE1FznP2OmDZHzliX1bSyYuG8 1e14WpSg==; Received: from [201.162.240.44] (port=7869 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j7fZ5-001Geq-SP; Fri, 28 Feb 2020 07:20:28 -0600 Date: Fri, 28 Feb 2020 07:23:23 -0600 From: "Gustavo A. R. Silva" To: Trond Myklebust , Anna Schumaker , "J. Bruce Fields" , Chuck Lever Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] sunrpc: Replace zero-length array with flexible-array member Message-ID: <20200228132323.GA20181@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: 201.162.240.44 X-Source-L: No X-Exim-ID: 1j7fZ5-001Geq-SP X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.162.240.44]:7869 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 17 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@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/linux/sunrpc/svc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 1afe38eb33f7..7f0a83451bc0 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -380,7 +380,7 @@ struct svc_deferred_req { struct cache_deferred_req handle; size_t xprt_hlen; int argslen; - __be32 args[0]; + __be32 args[]; }; struct svc_process_info {