From patchwork Wed Feb 12 19:28:07 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: 197375 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.1 required=3.0 tests=DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CD4FC352A4 for ; Wed, 12 Feb 2020 19:50:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00DA324671 for ; Wed, 12 Feb 2020 19:50:08 +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="YbFm2LNA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729051AbgBLTuI (ORCPT ); Wed, 12 Feb 2020 14:50:08 -0500 Received: from gateway33.websitewelcome.com ([192.185.146.68]:11330 "EHLO gateway33.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728767AbgBLTuI (ORCPT ); Wed, 12 Feb 2020 14:50:08 -0500 X-Greylist: delayed 1474 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Feb 2020 14:50:07 EST Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway33.websitewelcome.com (Postfix) with ESMTP id 957D5170F08 for ; Wed, 12 Feb 2020 13:25:33 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 1xddjW7urEfyq1xddjfpjT; Wed, 12 Feb 2020 13:25:33 -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=Yw0TNGO/aORoCtmP+MBqxiUhZyXSWK2un4Zm/19bNpU=; b=YbFm2LNA/HB7hYDqEuTGCOkYQC bxST4UXDTm2HiZ4KgZl0BUnokuStDzILXMNwzOR7Ffy1ccPO3Jb8gDtS+FpUBfJecTjO/+MybiDam rjOfb7yjeib2GOEgFRqYBQLtlzl+0R6+yO2eVNwj5mRhUCs3Gey2PDisW6hJWv/+OmBQk1y6q4Xe+ EX0F882QfjId4sjDTN8NNHpCd8oDer37TlY+Ot0wtHJXsBcdDw92SzA+BotY8vnGGhVzs2Z2U3NJ+ DLyxaqZVFpcaFQAACEul6k6C3M6STZFQmYMo5i/DGsUnT/rk9XOdLtYLsrfk3Jldh5sXmYXediAcB imq9A1Jg==; Received: from [201.144.174.25] (port=30860 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j1xdb-0014wK-SO; Wed, 12 Feb 2020 13:25:32 -0600 Date: Wed, 12 Feb 2020 13:28:07 -0600 From: "Gustavo A. R. Silva" To: Marcel Holtmann , Johan Hedberg Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] Bluetooth: btintel: Replace zero-length array with flexible-array member Message-ID: <20200212192807.GA25300@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: 201.144.174.25 X-Source-L: No X-Exim-ID: 1j1xdb-0014wK-SO X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.144.174.25]:30860 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 7 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@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 inadvertenly 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/bluetooth/btintel.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/bluetooth/btintel.c b/drivers/bluetooth/btintel.c index 62e781a18bf0..6a0e2c5a8beb 100644 --- a/drivers/bluetooth/btintel.c +++ b/drivers/bluetooth/btintel.c @@ -376,13 +376,13 @@ struct ibt_cp_reg_access { __le32 addr; __u8 mode; __u8 len; - __u8 data[0]; + __u8 data[]; } __packed; struct ibt_rp_reg_access { __u8 status; __le32 addr; - __u8 data[0]; + __u8 data[]; } __packed; static int regmap_ibt_read(void *context, const void *addr, size_t reg_size,