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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 BE086C433E6 for ; Fri, 5 Mar 2021 03:25:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BE4264FEE for ; Fri, 5 Mar 2021 03:25:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229580AbhCEDZF (ORCPT ); Thu, 4 Mar 2021 22:25:05 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:13060 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229458AbhCEDZF (ORCPT ); Thu, 4 Mar 2021 22:25:05 -0500 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DsCjR3kjszMjHB; Fri, 5 Mar 2021 11:22:51 +0800 (CST) Received: from [10.67.102.197] (10.67.102.197) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.498.0; Fri, 5 Mar 2021 11:24:55 +0800 Subject: Re: [PATCH 4/4] nfc: Avoid endless loops caused by repeated llcp_sock_connect()(Internet mail) To: =?UTF-8?B?a2l5aW4o5bC55LquKQ==?= , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , "gregkh@linuxfoundation.org" , "sameo@linux.intel.com" , "linville@tuxdriver.com" , "davem@davemloft.net" , "kuba@kernel.org" , "mkl@pengutronix.de" , "stefan@datenfreihafen.org" , "matthieu.baerts@tessares.net" , "netdev@vger.kernel.org" CC: "wangle6@huawei.com" , "xiaoqian9@huawei.com" References: <20210303061654.127666-1-nixiaoming@huawei.com> <20210303061654.127666-5-nixiaoming@huawei.com> <2965a9b88d254b7f8e7f4356875bbedb@tencent.com> From: Xiaoming Ni Message-ID: <9295c052-a9e2-619c-eb40-87b592e2c08d@huawei.com> Date: Fri, 5 Mar 2021 11:24:55 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.0.1 MIME-Version: 1.0 In-Reply-To: <2965a9b88d254b7f8e7f4356875bbedb@tencent.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.102.197] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/3/3 17:28, kiyin(尹亮) wrote: > Hi xiaoming, > the path can only fix the endless loop problem. it can't fix the meaningless llcp_sock->service_name problem. > if we set llcp_sock->service_name to meaningless string, the connect will be failed. and sk->sk_state will not be LLCP_CONNECTED. then we can call llcp_sock_connect() many times. that leaks everything: llcp_sock->dev, llcp_sock->local, llcp_sock->ssap, llcp_sock->service_name... I didn't find the code to modify sk->sk_state after a connect failure. Can you provide guidance? Based on my understanding of the current code: After llcp_sock_connect() is invoked using the meaningless service_name as the parameter, sk->sk_state is set to LLCP_CONNECTING. After that, no corresponding service responds to the request because the service_name is meaningless, the value of sk->sk_state remains unchanged. Therefore, when llcp_sock_connect() is invoked again, resources such as llcp_sock->service_name are not repeatedly applied because sk_state is set to LLCP_CONNECTING. In this way, the repeated invoking of llcp_sock_connect() does not repeatedly leak resources. Thanks Xiaoming Ni > >> -----Original Message----- >> From: Xiaoming Ni [mailto:nixiaoming@huawei.com] >> Sent: Wednesday, March 3, 2021 2:17 PM >> To: linux-kernel@vger.kernel.org; kiyin(尹亮) ; >> stable@vger.kernel.org; gregkh@linuxfoundation.org; sameo@linux.intel.com; >> linville@tuxdriver.com; davem@davemloft.net; kuba@kernel.org; >> mkl@pengutronix.de; stefan@datenfreihafen.org; >> matthieu.baerts@tessares.net; netdev@vger.kernel.org >> Cc: nixiaoming@huawei.com; wangle6@huawei.com; xiaoqian9@huawei.com >> Subject: [PATCH 4/4] nfc: Avoid endless loops caused by repeated >> llcp_sock_connect()(Internet mail) >> >> When sock_wait_state() returns -EINPROGRESS, "sk->sk_state" is >> LLCP_CONNECTING. In this case, llcp_sock_connect() is repeatedly invoked, >> nfc_llcp_sock_link() will add sk to local->connecting_sockets twice. >> sk->sk_node->next will point to itself, that will make an endless loop and >> hang-up the system. >> To fix it, check whether sk->sk_state is LLCP_CONNECTING in >> llcp_sock_connect() to avoid repeated invoking. >> >> fix CVE-2020-25673 >> Fixes: b4011239a08e ("NFC: llcp: Fix non blocking sockets connections") >> Reported-by: "kiyin(尹亮)" >> Link: https://www.openwall.com/lists/oss-security/2020/11/01/1 >> Cc: #v3.11 >> Signed-off-by: Xiaoming Ni >> --- >> net/nfc/llcp_sock.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c index >> 59172614b249..a3b46f888803 100644 >> --- a/net/nfc/llcp_sock.c >> +++ b/net/nfc/llcp_sock.c >> @@ -673,6 +673,10 @@ static int llcp_sock_connect(struct socket *sock, >> struct sockaddr *_addr, >> ret = -EISCONN; >> goto error; >> } >> + if (sk->sk_state == LLCP_CONNECTING) { >> + ret = -EINPROGRESS; >> + goto error; >> + } >> >> dev = nfc_get_device(addr->dev_idx); >> if (dev == NULL) { >> -- >> 2.27.0 >> >