From mboxrd@z Thu Jan 1 00:00:00 1970 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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 9783CC38A2A for ; Thu, 7 May 2020 19:01:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DFA721835 for ; Thu, 7 May 2020 19:01:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588878085; bh=zVXmqoLDVD2WgpBRe4UKXv7/cwYfVjp6DI3tW4V29fY=; h=Date:From:To:Cc:Subject:List-ID:From; b=0WWpYmbV7dfaGzLqvdZxVa79FxKPc6f1HFIvY58HCvG6bss7AmECTXX4kl13dk2M5 9P7+oo/XZXjS2pnnJJID93DFRQcG4w/indLiY7IRRVu0B7rC+lqk1KslzEFy/kwBb5 GKZUgxo2ZbUNa7z+KGhQW97RJdcPFbsUT/bhVGK0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728444AbgEGTBY (ORCPT ); Thu, 7 May 2020 15:01:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:32860 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726320AbgEGTBX (ORCPT ); Thu, 7 May 2020 15:01:23 -0400 Received: from embeddedor (unknown [189.207.59.248]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3DE242083B; Thu, 7 May 2020 19:01:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588878082; bh=zVXmqoLDVD2WgpBRe4UKXv7/cwYfVjp6DI3tW4V29fY=; h=Date:From:To:Cc:Subject:From; b=E9FZWmoH2xfmdJj3SKjckcSoz/Qsc3bWTppwIoGvtGgrmUWGrVSIQe9hLD8jqhVmo RWo5CbElxmoYiv3rHB8emNc4ryBKizulFOQ4cMpyxZOkBqXfIm31XERDEv/Wfu736G f+DaSb2Y1WhHW7KT6yR361U7k42yawGMW3QC1ScA= Date: Thu, 7 May 2020 14:05:49 -0500 From: "Gustavo A. R. Silva" To: Dominik Brodowski Cc: linux-kernel@vger.kernel.org Subject: [PATCH] pcmcia: Replace zero-length array with flexible-array Message-ID: <20200507190549.GA15653@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) 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] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. 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/pcmcia/cistpl.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/pcmcia/cistpl.h b/include/pcmcia/cistpl.h index 59a011101e0e..749320cc9aba 100644 --- a/include/pcmcia/cistpl.h +++ b/include/pcmcia/cistpl.h @@ -161,7 +161,7 @@ typedef struct cistpl_funcid_t { typedef struct cistpl_funce_t { u_char type; - u_char data[0]; + u_char data[]; } cistpl_funce_t; /*====================================================================== @@ -255,7 +255,7 @@ typedef struct cistpl_data_serv_t { u_char escape; u_char encrypt; u_char misc_features; - u_char ccitt_code[0]; + u_char ccitt_code[]; } cistpl_data_serv_t; typedef struct cistpl_fax_serv_t { @@ -265,7 +265,7 @@ typedef struct cistpl_fax_serv_t { u_char encrypt; u_char features_0; u_char features_1; - u_char ccitt_code[0]; + u_char ccitt_code[]; } cistpl_fax_serv_t; typedef struct cistpl_voice_serv_t {