Received: by 2002:a25:c205:0:0:0:0:0 with SMTP id s5csp347710ybf; Wed, 26 Feb 2020 14:21:53 -0800 (PST) X-Google-Smtp-Source: APXvYqwNj42I15p9jqcqmEAeidYTSJp0KymG63R82dv4xXsYR/vdrCdOVsPNcw7f1znbTrwzwB12 X-Received: by 2002:a9d:6181:: with SMTP id g1mr901219otk.104.1582755713377; Wed, 26 Feb 2020 14:21:53 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1582755713; cv=none; d=google.com; s=arc-20160816; b=gxDzuWSbkOFJB5ySqrxa61vPiXWvR6KZPwpsSIdsnXLipbcR9WNQ1b5xZTOwplaE90 i34OTXjFjR9vlQxJo5DnPoSkxgLFKN06UurLWE+EdvNj3moBmUuTVOdEjn3y+yn3IwES skO1jRUs14rL/sSs+Ev3NV2Mwzx/3dgMR3xGMP/N03fWKFyGvykd9Ipj8+Gdn6Sl51/j PP6pNB0jmllaJlGdii4eEDODq5fscZvpCV7UvV81IizUlYDqCTRAPmq2sJrEGyRPlLFu SLUHTXUT0irl0R1fZCKqSAZP7nogpbH2PRwGo1eawzhrv9NQa5191LcQZlmZQfRgsfoa 3tEg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:content-disposition :mime-version:message-id:subject:cc:to:from:date:dkim-signature; bh=CYTLc8pzQUmhST1gNF70buho/8DcO3iBpI5E0Ps5vfs=; b=jZ30ASKNWE8ydy5e3u8hd6xWSQAIQm7HkWdZoGfU3GjI54VrELXlunL8hM7ldfn49u 3VDP8+OgYXLAkhpA57kFC9xC190itC9tR2fqFwjDwGlw8KwCwOaOapK04YmNmTmiFoQF 3dojeDpYbN50aN9MZ/r4M7D11BW9nLcv921/hLKacK+RTG+5/ool8Ymg0eBJPGoIlIAZ YhpI0VVAA2AZgQalGek+kK/b0dNMBPRcXF+vXpodxz+Q2/OnAm0Hxvq4rdvdaEL48YMU cvaisK+62UD3GHzqAbHmoq/rnP95W+JX/O8/Ns/8stlXFv3PVDmn4DetOAqbESz4x0Ew 18Pw== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@embeddedor.com header.s=default header.b="hTtWr/rd"; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id k125si301574oib.212.2020.02.26.14.21.41; Wed, 26 Feb 2020 14:21:53 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@embeddedor.com header.s=default header.b="hTtWr/rd"; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727902AbgBZWUQ (ORCPT + 99 others); Wed, 26 Feb 2020 17:20:16 -0500 Received: from gateway31.websitewelcome.com ([192.185.143.31]:11729 "EHLO gateway31.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727709AbgBZWUQ (ORCPT ); Wed, 26 Feb 2020 17:20:16 -0500 Received: from cm14.websitewelcome.com (cm14.websitewelcome.com [100.42.49.7]) by gateway31.websitewelcome.com (Postfix) with ESMTP id 1680744C75 for ; Wed, 26 Feb 2020 16:19:50 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 751yjH6i4XVkQ751yjcJXT; Wed, 26 Feb 2020 16:19:50 -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=CYTLc8pzQUmhST1gNF70buho/8DcO3iBpI5E0Ps5vfs=; b=hTtWr/rdD8SusMKMAi5uEL8juy dZ47G5Sct45sZijelNMJKhUg18pT1s0/d9NzSEZjOcU4I/wb6kR72CiR7oFBeb3HIlCWq5IIv8bvm yYK8yDuO6cwb5MBZJGiL5j41lRRfDtT/0qesFj5EVohGUejlqcEj++uSyLGI0tV1UZPRyOEZ8j6YU nxOyyfP4bqYbe9Rx2GypCzmS37+Uwd47VNEUBVF65as/wZmB23uYScHruywbXdS9Vopp+K9A2gRWn E9OAPJHPcLHsO7rfunENjPgARy/xyFybE40Kb71ZfKTh9EX2SQP4idDZ+zD+nf/tRYN0q/MZcd5tw 7mjcoH+Q==; Received: from [201.166.157.20] (port=49854 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j751w-001Htv-8f; Wed, 26 Feb 2020 16:19:48 -0600 Date: Wed, 26 Feb 2020 16:22:40 -0600 From: "Gustavo A. R. Silva" To: Tomas Winkler , Arnd Bergmann , Greg Kroah-Hartman , Dimitri Sivanich Cc: linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] misc: Replace zero-length array with flexible-array member Message-ID: <20200226222240.GA14474@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: 201.166.157.20 X-Source-L: No X-Exim-ID: 1j751w-001Htv-8f X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.166.157.20]:49854 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 10 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 --- drivers/misc/mei/hw.h | 2 +- drivers/misc/mei/mei_dev.h | 2 +- drivers/misc/sgi-gru/grulib.h | 2 +- drivers/misc/sgi-gru/grutables.h | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/misc/mei/hw.h b/drivers/misc/mei/hw.h index 8231b6941adf..b1a8d5ec88b3 100644 --- a/drivers/misc/mei/hw.h +++ b/drivers/misc/mei/hw.h @@ -216,7 +216,7 @@ struct mei_msg_hdr { struct mei_bus_message { u8 hbm_cmd; - u8 data[0]; + u8 data[]; } __packed; /** diff --git a/drivers/misc/mei/mei_dev.h b/drivers/misc/mei/mei_dev.h index 76f8ff5ff974..3a29db07211d 100644 --- a/drivers/misc/mei/mei_dev.h +++ b/drivers/misc/mei/mei_dev.h @@ -533,7 +533,7 @@ struct mei_device { #endif /* CONFIG_DEBUG_FS */ const struct mei_hw_ops *ops; - char hw[0] __aligned(sizeof(void *)); + char hw[] __aligned(sizeof(void *)); }; static inline unsigned long mei_secs_to_jiffies(unsigned long sec) diff --git a/drivers/misc/sgi-gru/grulib.h b/drivers/misc/sgi-gru/grulib.h index e77d1b1f9d05..85c103923632 100644 --- a/drivers/misc/sgi-gru/grulib.h +++ b/drivers/misc/sgi-gru/grulib.h @@ -136,7 +136,7 @@ struct gru_dump_context_header { pid_t pid; unsigned long vaddr; int cch_locked; - unsigned long data[0]; + unsigned long data[]; }; /* diff --git a/drivers/misc/sgi-gru/grutables.h b/drivers/misc/sgi-gru/grutables.h index a7e44b2eb413..5ce8f3081e96 100644 --- a/drivers/misc/sgi-gru/grutables.h +++ b/drivers/misc/sgi-gru/grutables.h @@ -372,7 +372,7 @@ struct gru_thread_state { int ts_data_valid; /* Indicates if ts_gdata has valid data */ struct gru_gseg_statistics ustats; /* User statistics */ - unsigned long ts_gdata[0]; /* save area for GRU data (CB, + unsigned long ts_gdata[]; /* save area for GRU data (CB, DS, CBE) */ }; -- 2.25.0