From patchwork Thu Mar 19 22:51:33 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: 11448171 X-Patchwork-Delegate: kvalo@adurom.com 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 16EAC14B4 for ; Thu, 19 Mar 2020 22:51:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E97332076C for ; Thu, 19 Mar 2020 22:51:38 +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="PotKNb+o" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727565AbgCSWvh (ORCPT ); Thu, 19 Mar 2020 18:51:37 -0400 Received: from gateway32.websitewelcome.com ([192.185.145.115]:33939 "EHLO gateway32.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726975AbgCSWvg (ORCPT ); Thu, 19 Mar 2020 18:51:36 -0400 Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway32.websitewelcome.com (Postfix) with ESMTP id E8E71A335DC for ; Thu, 19 Mar 2020 17:51:35 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id F40ljZdCr8vkBF40ljQelg; Thu, 19 Mar 2020 17:51:35 -0500 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=3GUe41RpPlWxlU4UBdpwU27X24kKmhrLlmW78YqosvU=; b=PotKNb+ojypKAQcTZXqn6if3jp Srm3U3QXP+I2eCm3vRPlhyNZvf+iMxuwAbk8RNsE/azcr+xZ4O2g3wyazkYL5U7ufaSPXnwxmTdtR JDqNhHWzZxzBw9Y3D2YbDLbenraJDPcPfg9DXxtWbUSx8/xa8UtGsBiMOclsqHxfGrTsdYjQ9DiC3 5xFy1289MlR6RdXR4hL9jY291Kan/s7WO+xylOcX1JJjiV/bv9q3vnr1x0Y32AWtyv9Lq3o0keQKM tx8WI2gC5VtMPenvh5fVDfjqLnk8SzoMbiYe0HBI7+LRgVfc34WjXzlbfNVQB78md2Duj2oHc3any hiyLBVZQ==; Received: from cablelink-189-218-116-241.hosts.intercable.net ([189.218.116.241]:54002 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.92) (envelope-from ) id 1jF40k-002HVt-1I; Thu, 19 Mar 2020 17:51:34 -0500 Date: Thu, 19 Mar 2020 17:51:33 -0500 From: "Gustavo A. R. Silva" To: Kalle Valo , "David S. Miller" Cc: linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] atmel: at76c50x-usb.h: Replace zero-length array with flexible-array member Message-ID: <20200319225133.GA29672@embeddedor.com> 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: 189.218.116.241 X-Source-L: No X-Exim-ID: 1jF40k-002HVt-1I X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: cablelink-189-218-116-241.hosts.intercable.net (embeddedor) [189.218.116.241]:54002 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 52 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@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/wireless/atmel/at76c50x-usb.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/atmel/at76c50x-usb.h b/drivers/net/wireless/atmel/at76c50x-usb.h index f56863403b05..746e64dfd8aa 100644 --- a/drivers/net/wireless/atmel/at76c50x-usb.h +++ b/drivers/net/wireless/atmel/at76c50x-usb.h @@ -151,7 +151,7 @@ struct at76_command { u8 cmd; u8 reserved; __le16 size; - u8 data[0]; + u8 data[]; } __packed; /* Length of Atmel-specific Rx header before 802.11 frame */