From patchwork Thu May 7 15:17:58 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: 11534309 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 D6CC81392 for ; Thu, 7 May 2020 15:13:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BFC66207DD for ; Thu, 7 May 2020 15:13:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588864419; bh=GTM2+eUOtQwa+GzRb1C4IYjJnbBggbNRXgYQGHV5x9A=; h=Date:From:To:Cc:Subject:List-ID:From; b=T/ZDOFeq0SaUxwcQDI7DgtuwHn3nPrA5ytvMBQ3ol6r8VPrzxKWgv07ylvSeF7vzM ripACGui5j30Xz/XG+9orNHIWt3TMRG2E0dMNeyzeMxTsAeX0PxJD4RJDx6ih9gDxT rCQl+kROujLocxTlE58At5PQz79C4ZPxLlCIr+eM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728097AbgEGPNe (ORCPT ); Thu, 7 May 2020 11:13:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:42042 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727945AbgEGPNe (ORCPT ); Thu, 7 May 2020 11:13:34 -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 42AF420936; Thu, 7 May 2020 15:13:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588864413; bh=GTM2+eUOtQwa+GzRb1C4IYjJnbBggbNRXgYQGHV5x9A=; h=Date:From:To:Cc:Subject:From; b=y3WWJF3pJSf1WcaUBDe37+/p02rqqfNAnvOmXlDx0p1T9syX7iGkiuC5STccIAiPn wbj/8lguQ9yaPDCwmud1DJyW1vPnBqGDeO7MA2Rk/nqe1uvMMWgXf2IAbZJjB5jJgD 0ZkSonIJUv+yDvHwaOaYErDLKF/Unjt6pZuHDeMU= Date: Thu, 7 May 2020 10:17:58 -0500 From: "Gustavo A. R. Silva" To: Kalle Valo , "David S. Miller" , Maxime Coquelin , Alexandre Torgue Cc: wcn36xx@lists.infradead.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, "Gustavo A. R. Silva" Subject: [PATCH] wcn36xx: Replace zero-length array with flexible-array Message-ID: <20200507151758.GA4962@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) 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] 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 --- drivers/net/wireless/ath/wcn36xx/hal.h | 4 ++-- drivers/net/wireless/ath/wcn36xx/testmode.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/wireless/ath/wcn36xx/hal.h b/drivers/net/wireless/ath/wcn36xx/hal.h index 6ba0fd57c951..aab5a58616fc 100644 --- a/drivers/net/wireless/ath/wcn36xx/hal.h +++ b/drivers/net/wireless/ath/wcn36xx/hal.h @@ -2240,7 +2240,7 @@ struct wcn36xx_hal_process_ptt_msg_req_msg { struct wcn36xx_hal_msg_header header; /* Actual FTM Command body */ - u8 ptt_msg[0]; + u8 ptt_msg[]; } __packed; struct wcn36xx_hal_process_ptt_msg_rsp_msg { @@ -2249,7 +2249,7 @@ struct wcn36xx_hal_process_ptt_msg_rsp_msg { /* FTM Command response status */ u32 ptt_msg_resp_status; /* Actual FTM Command body */ - u8 ptt_msg[0]; + u8 ptt_msg[]; } __packed; struct update_edca_params_req_msg { diff --git a/drivers/net/wireless/ath/wcn36xx/testmode.h b/drivers/net/wireless/ath/wcn36xx/testmode.h index 4c6cfdb46580..09d68fab9add 100644 --- a/drivers/net/wireless/ath/wcn36xx/testmode.h +++ b/drivers/net/wireless/ath/wcn36xx/testmode.h @@ -20,7 +20,7 @@ struct ftm_rsp_msg { u16 msg_id; u16 msg_body_length; u32 resp_status; - u8 msg_response[0]; + u8 msg_response[]; } __packed; /* The request buffer of FTM which contains a byte of command and the request */