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From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 10 Dec 2020 15:53:09 +0100
Message-ID: <CANn89iLFCBVOzPhwSxmAnT6dx8fnRD4TYRSJaX2ni7AxvXKEGg@mail.gmail.com>
Subject: Re: [PATCH 4.4 15/39] geneve: pull IP header before ECN decapsulation
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org,
        syzbot <syzkaller@googlegroups.com>,
        Jakub Kicinski <kuba@kernel.org>
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On Thu, Dec 10, 2020 at 3:40 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Thu, Dec 10, 2020 at 03:38:44PM +0100, Greg Kroah-Hartman wrote:
> > On Thu, Dec 10, 2020 at 03:32:12PM +0100, Eric Dumazet wrote:
> > > On Thu, Dec 10, 2020 at 3:26 PM Greg Kroah-Hartman
> > > <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > From: Eric Dumazet <edumazet@google.com>
> > > >
> > > > IP_ECN_decapsulate() and IP6_ECN_decapsulate() assume
> > > > IP header is already pulled.
> > > >
> > > > geneve does not ensure this yet.
> > > >
> > > > Fixing this generically in IP_ECN_decapsulate() and
> > > > IP6_ECN_decapsulate() is not possible, since callers
> > > > pass a pointer that might be freed by pskb_may_pull()
> > > >
> > > > syzbot reported :
> > > >
> > >
> > > Note that we had to revert this patch, so you can either scratp this
> > > backport, or make sure to backport the revert.
> >
> > I'll drop it thanks.  Odd I lost the upstream git id on this patch, let
> > me check what went wrong...
>
> What is the git id of the revert?  This ended up already in 4.19.y,
> 5.4.y, and 5.9.y so needs to be reverted there.
>

https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=c02bd115b1d25931159f89c7d9bf47a30f5d4b41

Thanks !

> thanks,
>
> greg k-h