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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Sat, 16 Mar 2019 17:07:13 +0100
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Subject: Re: KASAN: slab-out-of-bounds Read in tick_sched_handle
To:     Stefano Brivio <sbrivio@redhat.com>
Cc:     syzbot <syzbot+09d51a30df9fe76edb2a@syzkaller.appspotmail.com>,
        David Miller <davem@davemloft.net>,
        =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= <fweisbec@gmail.com>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Sabrina Dubroca <sd@queasysnail.net>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Eric Dumazet <eric.dumazet@gmail.com>
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On Sat, Mar 16, 2019 at 4:53 PM Stefano Brivio <sbrivio@redhat.com> wrote:
>
> On Sat, 16 Mar 2019 07:49:01 -0700
> syzbot <syzbot+09d51a30df9fe76edb2a@syzkaller.appspotmail.com> wrote:
>
> > syzbot has bisected this bug to:
> >
> > commit b8a51b38e4d4dec3e379d52c0fe1a66827f7cf1e
> > Author: Stefano Brivio <sbrivio@redhat.com>
> > Date:   Thu Nov 8 11:19:23 2018 +0000
> >
> >      fou, fou6: ICMP error handlers for FoU and GUE
> >
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16f943e7200000
> > start commit:   b8a51b38 fou, fou6: ICMP error handlers for FoU and GUE
> > git tree:       upstream
> > final crash:    https://syzkaller.appspot.com/x/report.txt?x=15f943e7200000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=11f943e7200000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=b05cfdb4ee8ab9b2
> > dashboard link: https://syzkaller.appspot.com/bug?extid=09d51a30df9fe76edb2a
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17359fab400000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=154a2a37400000
> >
> > Reported-by: syzbot+09d51a30df9fe76edb2a@syzkaller.appspotmail.com
> > Fixes: b8a51b38 ("fou, fou6: ICMP error handlers for FoU and GUE")
>
> Might be fixed by bc6e019b6ee6 ("fou: Prevent unbounded recursion in GUE
> error handler also with UDP-Lite"), testing/checking now.

Yes, most likely it is. The bug was just never closed as fixed. But
the last crash happened 2 months ago.
So I would say we just mark this as fixed:

#syz fix:
fou: Prevent unbounded recursion in GUE error handler also with UDP-Lite

Next after root cause bisection is fix bisection, so this part will be
automated to some degree as well.