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Date:   Mon, 2 Dec 2019 15:39:12 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
To:     Dmitry Vyukov <dvyukov@google.com>
Cc:     syzbot <syzbot+b2bf2652983d23734c5c@syzkaller.appspotmail.com>,
        David Miller <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        LKML <linux-kernel@vger.kernel.org>, linux-sctp@vger.kernel.org,
        Xin Long <lucien.xin@gmail.com>, mvohra@vmware.com,
        netdev <netdev@vger.kernel.org>,
        Neil Horman <nhorman@tuxdriver.com>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        William Tu <u9012063@gmail.com>,
        Vladislav Yasevich <vyasevich@gmail.com>,
        websitedesignservices4u@gmail.com,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Subject: Re: kernel BUG at net/core/skbuff.c:LINE! (3)
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On Sat, Nov 30, 2019 at 04:37:56PM +0100, Dmitry Vyukov wrote:
> On Sat, Nov 30, 2019 at 3:50 PM syzbot
> <syzbot+b2bf2652983d23734c5c@syzkaller.appspotmail.com> wrote:
> >
> > syzbot has bisected this bug to:
> >
> > commit 84e54fe0a5eaed696dee4019c396f8396f5a908b
> > Author: William Tu <u9012063@gmail.com>
> > Date:   Tue Aug 22 16:40:28 2017 +0000
> >
> >      gre: introduce native tunnel support for ERSPAN
> >
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=158a2f86e00000
> > start commit:   f9f1e414 Merge tag 'for-linus-4.16-rc1-tag' of git://git.k..
> > git tree:       upstream
> > final crash:    https://syzkaller.appspot.com/x/report.txt?x=178a2f86e00000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=138a2f86e00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=34a80ee1ac29767b
> > dashboard link: https://syzkaller.appspot.com/bug?extid=b2bf2652983d23734c5c
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=147bfebd800000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13d8d543800000
> >
> > Reported-by: syzbot+b2bf2652983d23734c5c@syzkaller.appspotmail.com
> > Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN")
> >
> > For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
> Humm... the repro contains syz_emit_ethernet, wonder if it's
> remote-triggerable...

The call trace is still from the tx path. Packet never left the system
in this case.