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=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 812EDC433E2 for ; Thu, 27 Aug 2020 23:35:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 541B820848 for ; Thu, 27 Aug 2020 23:35:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728094AbgH0XfU (ORCPT ); Thu, 27 Aug 2020 19:35:20 -0400 Received: from mail-proxy25223.qiye.163.com ([103.129.252.23]:12360 "EHLO mail-proxy25223.qiye.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728083AbgH0XfU (ORCPT ); Thu, 27 Aug 2020 19:35:20 -0400 Received: from [192.168.1.7] (unknown [101.81.69.209]) by m9785.mail.qiye.163.com (Hmail) with ESMTPA id 3AE005C0F66; Fri, 28 Aug 2020 07:33:12 +0800 (CST) Subject: Re: [PATCH net-next 1/2] ipv6: add ipv6_fragment hook in ipv6_stub To: Marcelo Ricardo Leitner , David Miller Cc: netdev@vger.kernel.org References: <1598524792-30597-1-git-send-email-wenxu@ucloud.cn> <1598524792-30597-2-git-send-email-wenxu@ucloud.cn> <20200827.075147.1030378285544511842.davem@davemloft.net> <20200827223836.GB2443@localhost.localdomain> From: wenxu Message-ID: <401c9afe-cc58-bf62-4588-b971b05cb024@ucloud.cn> Date: Fri, 28 Aug 2020 07:33:10 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200827223836.GB2443@localhost.localdomain> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgYFAkeWUFZS1VLWVdZKFlBSUI3V1ktWUFJV1kPCR oVCBIfWUFZSx8aHx5JSk0fS05PVkpOQkNOTEpKQklIQk9VGRETFhoSFyQUDg9ZV1kWGg8SFR0UWU FZT0tIVUpKS0hKTFVKS0tZBg++ X-HM-Sender-Digest: e1kMHhlZQR0aFwgeV1kSHx4VD1lBWUc6PhQ6PRw5OD5PIxlPAhE*Nhgp GktPFB9VSlVKTkJDTkxKSkJJTkpOVTMWGhIXVQweFQMOOw4YFxQOH1UYFUVZV1kSC1lBWUpLSlVD SlVNQlVJS0JZV1kIAVlBSUNDSzcG X-HM-Tid: 0a743244a0142087kuqy3ae005c0f66 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Yes， I check the ipv6_stub->ipv6_fragment. And in the case if there is no ipv6_stub->ipv6_fragment it means no ipv6 fragment support and it should free the skb. Maybe sometimes  not all the calling remember to check with this? So it should add a default one with following? +static int eafnosupport_ipv6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, +                                     int (*output)(struct net *, struct sock *, struct sk_buff *)) +{ +       kfree_skb(skb); +       return -EAFNOSUPPORT; +} + 在 2020/8/28 6:38, Marcelo Ricardo Leitner 写道: > On Thu, Aug 27, 2020 at 07:51:47AM -0700, David Miller wrote: >> From: wenxu@ucloud.cn >> Date: Thu, 27 Aug 2020 18:39:51 +0800 >> >>> From: wenxu >>> >>> Add ipv6_fragment to ipv6_stub to avoid calling netfilter when >>> access ip6_fragment. >>> >>> Signed-off-by: wenxu >> Please test these changes with ipv6 disabled. >> >> It will crash, you have to update the default stub in >> net/ipv6/addrconf_core.c as well. > I didn't test it myself but I'm not seeing how the crash could happen. > The next patch does check for it being NULL before using it: > > - if (!v6ops) > + if (!ipv6_stub->ipv6_fragment) > goto err; > > Wenxu? > > Marcelo >