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From:   Xin Long <lucien.xin@gmail.com>
Date:   Mon, 24 Jun 2019 12:38:59 +0800
Message-ID: <CADvbK_f0kZOZRUQ3eWNMiOUTC_JE6xsrdX2VzsHsAXKrq3D8ig@mail.gmail.com>
Subject: Re: KASAN: user-memory-access Read in ip6_hold_safe (3)
To:     Dmitry Vyukov <dvyukov@google.com>
Cc:     David Ahern <dsahern@gmail.com>,
        syzbot <syzbot+a5b6e01ec8116d046842@syzkaller.appspotmail.com>,
        David Miller <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
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On Mon, Jun 3, 2019 at 2:57 PM Dmitry Vyukov <dvyukov@google.com> wrote:
>
> On Sat, Jun 1, 2019 at 7:15 PM David Ahern <dsahern@gmail.com> wrote:
> >
> > On 6/1/19 12:05 AM, syzbot wrote:
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit:    dfb569f2 net: ll_temac: Fix compile error
> > > git tree:       net-next
> > syzbot team:
> >
> > Is there any way to know the history of syzbot runs to determine that
> > crash X did not happen at commit Y but does happen at commit Z? That
> > narrows the window when trying to find where a regression occurs.
>
> Hi David,
>
> All info is available on the dashboard:
>
> > dashboard link: https://syzkaller.appspot.com/bug?extid=a5b6e01ec8116d046842
>
> We don't keep any private info on top of that.
>
> This crash happened 129 times in the past 9 days. This suggests this
> is not a previous memory corruption, these usually happen at most few
> times.
> The first one was:
>
> 2019/05/24 15:33 net-next dfb569f2
>
> Then it was joined by bpf-next:
>
> ci-upstream-bpf-next-kasan-gce 2019/06/01 15:51 bpf-next 0462eaac
>
> Since it happens a dozen of times per day, most likely it was
> introduced into net-next around dfb569f2 (syzbot should do new builds
> every ~12h, minus broken trees).

I think all these pcpu memory corruptions can be marked as Fixed-by:

commit c3bcde026684c62d7a2b6f626dc7cf763833875c
Author: Xin Long <lucien.xin@gmail.com>
Date:   Mon Jun 17 21:34:15 2019 +0800

    tipc: pass tunnel dev as NULL to udp_tunnel(6)_xmit_skb