Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <000000000000513fb7057e8d7013@google.com>
In-Reply-To: <000000000000513fb7057e8d7013@google.com>
From:   Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date:   Thu, 3 Jan 2019 13:39:02 -0600
Message-ID: <CA+FuTSfnaL3asZg6oDdwk2J741Cf9fbVxGrB_2jdXgOwvvk+tA@mail.gmail.com>
Subject: Re: kernel panic: stack is corrupted in udp4_lib_lookup2
To:     syzbot <syzbot+4ad25edc7a33e4ab91e0@syzkaller.appspotmail.com>
Cc:     David Miller <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        syzkaller-bugs@googlegroups.com,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>, sbrivio@redhat.com
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Jan 3, 2019 at 7:07 AM syzbot
<syzbot+4ad25edc7a33e4ab91e0@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    195303136f19 Merge tag 'kconfig-v4.21-2' of git://git.kern..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=12245d8f400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5e7dc790609552d7
> dashboard link: https://syzkaller.appspot.com/bug?extid=4ad25edc7a33e4ab91e0
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+4ad25edc7a33e4ab91e0@syzkaller.appspotmail.com
>
> protocol 88fb is buggy, dev hsr_slave_1
> protocol 88fb is buggy, dev hsr_slave_0
> protocol 88fb is buggy, dev hsr_slave_1
> FAT-fs (loop0): invalid media value (0x00)
> FAT-fs (loop0): Can't find a valid FAT filesystem
> Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in:

This sounds similar to the stack corruption fixed recently in commit
e7cc082455cb ("udp: Support for error handlers of tunnels ...").

That fix is for ipv4 gue_err(). ipv6 gue6_err() probably needs the same.