From patchwork Wed Feb 12 19:31:19 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: 11379109 X-Patchwork-Delegate: marcel@holtmann.org 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 86A7C1395 for ; Wed, 12 Feb 2020 19:49:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6422324671 for ; Wed, 12 Feb 2020 19:49:21 +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="djvwU+Rt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728767AbgBLTtU (ORCPT ); Wed, 12 Feb 2020 14:49:20 -0500 Received: from gateway36.websitewelcome.com ([192.185.188.18]:40248 "EHLO gateway36.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727439AbgBLTtU (ORCPT ); Wed, 12 Feb 2020 14:49:20 -0500 X-Greylist: delayed 1233 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Feb 2020 14:49:19 EST Received: from cm13.websitewelcome.com (cm13.websitewelcome.com [100.42.49.6]) by gateway36.websitewelcome.com (Postfix) with ESMTP id 168F140955E0A for ; Wed, 12 Feb 2020 12:42:49 -0600 (CST) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id 1xgjj0ha9RP4z1xgjjSKhS; Wed, 12 Feb 2020 13:28:45 -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=GLQRqO9qBiBgvx5iIVYH7SAy6igUj4/Se4YJcTpd4Uc=; b=djvwU+RtA4hzE8ETixJL+QtaCH DPmZeGdoGlryypEb/bZCGw85EkV5aOI+Up5JbbulEpxubacWLqiFETsw/YNFcVRYLqQbU5IhyHsqo kqNxXDv9fpX9wCISf9bryT4alB2hy2cSFa3wMR71d1NFIxqAhB+J6iriahyU2E78HGQNpY03FbTDY SaR6BOe8aQ4aQcdXNFgGz+L0eRwxTre5U8iPSDK6K4RvPoj5Zczt+XfiKvaXrDxhxJsZ5n0HaX4Nk HgmoAioHcPEO+HJv7rugmZWVCw0D2zgYafZ10TRCRDCEf94Y95j3/1n+T4DopDWUu4dl+2mcxz/zY i+/Sqqkw==; Received: from [201.144.174.25] (port=14408 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1j1xgi-0016Mw-Gn; Wed, 12 Feb 2020 13:28:44 -0600 Date: Wed, 12 Feb 2020 13:31:19 -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: hci_intel: Replace zero-length array with flexible-array member Message-ID: <20200212193119.GA27048@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: 1j1xgi-0016Mw-Gn X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.144.174.25]:14408 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 15 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/hci_intel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/bluetooth/hci_intel.c b/drivers/bluetooth/hci_intel.c index 31f25153087d..f1299da6eed8 100644 --- a/drivers/bluetooth/hci_intel.c +++ b/drivers/bluetooth/hci_intel.c @@ -49,7 +49,7 @@ struct hci_lpm_pkt { __u8 opcode; __u8 dlen; - __u8 data[0]; + __u8 data[]; } __packed; struct intel_device {