netdev - Re: [PATCH] bpf: make sure mac_header was set before using it

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Date:   Thu, 7 Jul 2022 11:40:33 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Network Development <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, Eric Dumazet <eric.dumazet@...il.com>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: [PATCH] bpf: make sure mac_header was set before using it

On Thu, Jul 7, 2022 at 11:36 AM Eric Dumazet <edumazet@...gle.com> wrote:
>
> On Thu, Jul 7, 2022 at 8:31 PM Alexei Starovoitov
> <alexei.starovoitov@...il.com> wrote:
> >
> > On Thu, Jul 7, 2022 at 11:20 AM <patchwork-bot+netdevbpf@...nel.org> wrote:
> > >
> > > Hello:
> > >
> > > This patch was applied to bpf/bpf.git (master)
> >
> > Are we sure it's bpf tree material?
> > The fixes tag points to net-next tree.
>
> Fix is generic and should not harm bpf tree, or any tree if that matters.

Right. Just trying to understand the urgency/severity
considering we're at rc5.

> Sorry for not adding the net-next tag in the [PATCH].
>
> >
> > > by Daniel Borkmann <daniel@...earbox.net>:
> > >
> > > On Thu,  7 Jul 2022 12:39:00 +0000 you wrote:
> > > > Classic BPF has a way to load bytes starting from the mac header.
> > > >
> > > > Some skbs do not have a mac header, and skb_mac_header()
> > > > in this case is returning a pointer that 65535 bytes after
> > > > skb->head.
> > > >
> > > > Existing range check in bpf_internal_load_pointer_neg_helper()
> > > > was properly kicking and no illegal access was happening.
> > > >
> > > > [...]
> > >
> > > Here is the summary with links:
> > >   - bpf: make sure mac_header was set before using it
> > >     https://git.kernel.org/bpf/bpf/c/0326195f523a
> > >
> > > You are awesome, thank you!
> > > --
> > > Deet-doot-dot, I am a bot.
> > > https://korg.docs.kernel.org/patchwork/pwbot.html
> > >
> > >