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=-5.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 8F851C3A59C for ; Fri, 16 Aug 2019 08:24:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 604BA20644 for ; Fri, 16 Aug 2019 08:24:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="prY9zdy3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726882AbfHPIX7 (ORCPT ); Fri, 16 Aug 2019 04:23:59 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:36620 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726688AbfHPIX7 (ORCPT ); Fri, 16 Aug 2019 04:23:59 -0400 Received: by mail-wr1-f68.google.com with SMTP id r3so738913wrt.3 for ; Fri, 16 Aug 2019 01:23:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=TTv7ICEmJhqzfI5qGfgcsvSh9+fw95MkNOOVAZ/4kR8=; b=prY9zdy3xD3MpauN4Yf4eipXfCMngHI1u1pRYs2DqAJm0lFrVY089aIUa7s5z5Y8yJ 2kt3KUikDvDWp5iV75M490/X5HpZshu2Vw/xRPpyFYy1gIYI4nkPspYllvqiXF8+/eML 9khxs7C19YYBFwGWovY0mVgxvGbOK1InkCVU6XsT/agCg98BKEXZlcz+6Gz4sT3/kcfa cM6fsZgnACJHfo2VJCfy7mWTQD3IN+gvqHQkiD7ec2GYQ4d8s03+VV+Es1TLUO2aK3jv jXEG5tYm1cZj38TDDcl6/qynVN/bqFBX9XsA2dyJVbEqLm05zuwpCe0U9TbT2k0e2GOi 7o0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=TTv7ICEmJhqzfI5qGfgcsvSh9+fw95MkNOOVAZ/4kR8=; b=c2BXAq9eWwub6/H0Mt7l2PZTkw5kRShMfps08XbV+WRJTeaL9VUfhN5nv91esCGXy0 uTdQv8awvayuOlYyw4pvAFD5u5miF1LZAQCcHDAkkUPsXpV4Ebqi2d1jNRmmoK3qVZRj SRogSybc7x/n2uhqmlG60N2chBpY94gxVUjpqsK3OT4sX5aCQFULI1rh0TN3SUxpsUkE BGzxbpIU/6h5CZr0F+FZhM1+7ZbPH8p4xzkxXJO3j93mUB1TG7YR/USp3xFvAu9NK6yb RDX8zh1g5Dk1aAOcL8KFs+7Mqs+yUCmMyeojcMjVo47M+0/jQfbmNSjw7nurk7tbiltT hZtQ== X-Gm-Message-State: APjAAAXWJBcgrexBTN1lQLykzguj79CLRIwX++tuTtd/QbC1MYKngZeW s3QhnzpJRTuBBYPQhV9XHug= X-Google-Smtp-Source: APXvYqxmlRjxnEpeAmes3XBx29lSNZv1x7GcSVRjCFV75BE9rR3t5d6g251sVfz1b0noxcZ6e0kJpw== X-Received: by 2002:adf:bace:: with SMTP id w14mr8180449wrg.283.1565943836974; Fri, 16 Aug 2019 01:23:56 -0700 (PDT) Received: from [192.168.8.147] (187.170.185.81.rev.sfr.net. [81.185.170.187]) by smtp.gmail.com with ESMTPSA id f6sm8786693wrh.30.2019.08.16.01.23.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Aug 2019 01:23:56 -0700 (PDT) Subject: Re: [PATCH net] tunnel: fix dev null pointer dereference when send pkg larger than mtu in collect_md mode To: Hangbin Liu Cc: netdev@vger.kernel.org, Stefano Brivio , wenxu , Alexei Starovoitov , "David S . Miller" References: <20190815060904.19426-1-liuhangbin@gmail.com> <20190816032418.GX18865@dhcp-12-139.nay.redhat.com> From: Eric Dumazet Message-ID: Date: Fri, 16 Aug 2019 10:23:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190816032418.GX18865@dhcp-12-139.nay.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 8/16/19 5:24 AM, Hangbin Liu wrote: > Hi Eric, > > Thanks for the review. > On Thu, Aug 15, 2019 at 11:16:58AM +0200, Eric Dumazet wrote: >>> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c >>> index 38c02bb62e2c..c6713c7287df 100644 >>> --- a/net/ipv4/ip_tunnel.c >>> +++ b/net/ipv4/ip_tunnel.c >>> @@ -597,6 +597,9 @@ void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, >>> goto tx_error; >>> } >>> >>> + if (skb_dst(skb) && !skb_dst(skb)->dev) >>> + skb_dst(skb)->dev = rt->dst.dev; >>> + >> >> >> IMO this looks wrong. >> This dst seems shared. > > If the dst is shared, it may cause some problem. Could you point me where the > dst may be shared possibly? > dst are inherently shared. This is why we have a refcount on them. Only when the dst has been allocated by the current thread we can make changes on them.