netdev - Re: [PATCH bpf-next] bpf: test_bpf: add dummy dev->net for flow

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Message-ID: <CAF=yD-KPCipmYmR45Pa8fWLdH=jzcTAgbnXGbgeLQo78Oz4XNA@mail.gmail.com>
Date:   Thu, 27 Sep 2018 10:11:09 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     songliubraving@...com,
        Network Development <netdev@...r.kernel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>,
        Willem de Bruijn <willemb@...gle.com>,
        Petar Penkov <ppenkov@...gle.com>
Subject: Re: [PATCH bpf-next] bpf: test_bpf: add dummy dev->net for flow_dissector

On Thu, Sep 27, 2018 at 9:00 AM Eric Dumazet <eric.dumazet@...il.com> wrote:
>
>
>
> On 09/27/2018 12:15 AM, Song Liu wrote:
> > Latest changes in __skb_flow_dissect() assume skb->dev has valid nd_net.
> > However, this is not true for test_bpf. As a result, test_bpf.ko crashes
> > the system with the following stack trace:
> >
>
> > +     dev_net_set(&dev, &net);
>
> This is yet another fake stuff that will break some day, so many other things would
> need to be setup properly in a real "struct net"
>
> What about using the current net_ns ?
>
> dev_net_set(&dev, current->nsproxy->net_ns);
>
> This might be &init_net in the context of test_bpf(), so maybe simply use &init_net
> to clearly state that test_bpf is not net ns fully ready.

Agreed.

Thanks for fixing this.