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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 907C8C433EF for ; Mon, 30 May 2022 08:44:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234039AbiE3Iod (ORCPT ); Mon, 30 May 2022 04:44:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57378 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231968AbiE3Io3 (ORCPT ); Mon, 30 May 2022 04:44:29 -0400 Received: from mail.meizu.com (edge07.meizu.com [112.91.151.210]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6AE64D601 for ; Mon, 30 May 2022 01:44:26 -0700 (PDT) Received: from IT-EXMB-1-125.meizu.com (172.16.1.125) by mz-mail11.meizu.com (172.16.1.15) with Microsoft SMTP Server (TLS) id 14.3.487.0; Mon, 30 May 2022 16:44:24 +0800 Received: from [172.16.137.70] (172.16.137.70) by IT-EXMB-1-125.meizu.com (172.16.1.125) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.14; Mon, 30 May 2022 16:44:24 +0800 Message-ID: <6dd82c76-3064-3647-c08a-7d4e93d941d7@meizu.com> Date: Mon, 30 May 2022 16:44:23 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH] staging: rtl8712: Fix pointer dereferenced before checking To: Greg Kroah-Hartman CC: Larry Finger , Florian Schilhabel , , References: <1653897933-25931-1-git-send-email-baihaowen@meizu.com> <61130a41-a626-c860-e321-9295f9c9d0dd@meizu.com> From: baihaowen In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [172.16.137.70] X-ClientProxiedBy: IT-EXMB-1-126.meizu.com (172.16.1.126) To IT-EXMB-1-125.meizu.com (172.16.1.125) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/5/30 下午4:26, Greg Kroah-Hartman 写道: > On Mon, May 30, 2022 at 04:22:11PM +0800, baihaowen wrote: >> 在 2022/5/30 下午4:14, Greg Kroah-Hartman 写道: >>> On Mon, May 30, 2022 at 04:05:32PM +0800, Haowen Bai wrote: >>>> The padapter->recvpriv.signal_qual_data is dereferencing before null >>>> checking, so move it after checking. >>>> >>>> Signed-off-by: Haowen Bai >>>> --- >>>> drivers/staging/rtl8712/rtl8712_recv.c | 4 +++- >>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/staging/rtl8712/rtl8712_recv.c b/drivers/staging/rtl8712/rtl8712_recv.c >>>> index 7f1fdd058551..8ed94b259dbe 100644 >>>> --- a/drivers/staging/rtl8712/rtl8712_recv.c >>>> +++ b/drivers/staging/rtl8712/rtl8712_recv.c >>>> @@ -863,10 +863,12 @@ static void process_link_qual(struct _adapter *padapter, >>>> { >>>> u32 last_evm = 0, tmpVal; >>>> struct rx_pkt_attrib *pattrib; >>>> - struct smooth_rssi_data *sqd = &padapter->recvpriv.signal_qual_data; >>>> + struct smooth_rssi_data *sqd; >>>> >>>> if (!prframe || !padapter) >>>> return; >>>> + >>>> + sqd = &padapter->recvpriv.signal_qual_data; >>> How can padapter ever be NULL in this codepath? >>> >>> thanks, >>> >>> greg k-h >> Just the original  code, show me >> >> if (!prframe || !padapter) >> >> It would be null, and then return. > Again, trace things backwards, how can padapter ever be NULL? padapter will not be null, since it's initialized by netdev_priv(pnetdev) and return if pnetdev is null. r871xu_drv_init() ...... pnetdev = r8712_init_netdev(); if (!pnetdev) goto error; padapter = netdev_priv(pnetdev); status = r8712_init_drv_sw(padapter); ...... -- Haowen Bai