Message-ID: <1496891711.736.55.camel@edumazet-glaptop3.roam.corp.google.com>
Subject: Re: [PATCH v2 1/2] ip_tunnel: fix potential issue in ip_tunnel_rcv
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Pravin Shelar <pshelar@ovn.org>
Cc: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>,
        "=David S. Miller" <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        James Morris <jmorris@namei.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Patrick McHardy <kaber@trash.net>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        linux-kernel@vger.kernel.org, Pravin B Shelar <pshelar@nicira.com>,
        Haishuang Yan <yanhaishuang@cmss.chinamobile.com390e>
Date: Wed, 07 Jun 2017 20:15:11 -0700
In-Reply-To: <CAOrHB_CZ-3TRs2O3KATW_ji_QQxqO=28UeDU_-Gx7ZPxz_RWCg@mail.gmail.com>
References: <1496883476-17445-1-git-send-email-yanhaishuang@cmss.chinamobile.com>
         <CAOrHB_CZ-3TRs2O3KATW_ji_QQxqO=28UeDU_-Gx7ZPxz_RWCg@mail.gmail.com>
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On Wed, 2017-06-07 at 19:13 -0700, Pravin Shelar wrote:
> On Wed, Jun 7, 2017 at 5:57 PM, Haishuang Yan
> <yanhaishuang@cmss.chinamobile.com> wrote:
> > When ip_tunnel_rcv fails, the tun_dst won't be freed, so move
> > skb_dst_set to begin and tun_dst would be freed by kfree_skb.
> >
> > CC: Pravin B Shelar <pshelar@nicira.com>
> > Fixes: 2e15ea390e6f ("ip_gre: Add support to collect tunnel metadata.")
> > Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com390e>
> > ---
> >  net/ipv4/ip_tunnel.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
> > index b878ecb..27fc20f 100644
> > --- a/net/ipv4/ip_tunnel.c
> > +++ b/net/ipv4/ip_tunnel.c
> > @@ -386,6 +386,9 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
> >         const struct iphdr *iph = ip_hdr(skb);
> >         int err;
> >
> > +       if (tun_dst)
> > +               skb_dst_set(skb, (struct dst_entry *)tun_dst);
> > +
> If dst is set so early, skb_scrub_packet() would remove the tunnel dst
> reference.
> It is better to call skb_dst_drop() from error code path.

Do we really want to keep a dst from another namespace if
skb_scrub_packet() is called with xnet=true ?