Kernel panic on 5.3.1-arch1-1-ARCH

Kernel panic on 5.3.1-arch1-1-ARCH

[Nico Schottelius]

Hello,

loading the kernel module and starting wg-quick causes a kernel panic on
Arch Linux w/ the above mentioned kernel. I have uploaded a camera based
screen shot to

https://www.nico.schottelius.org/temp/IMG_20191005_221751.jpg

I tried both the wireguard-arch and wireguard-dkms approach, both led to
the same result.

Does this help anyone to debug the issue?

Best regards,

Nico


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Re: Kernel panic on 5.3.1-arch1-1-ARCH

[Jason A. Donenfeld]

This isn't WireGuard, actually. It's a line in wg-quick's bash that
says `ip rule add ... suppress_prefix ...`.

You can reproduce the kernel crash without WireGuard anywhere in the
equation with this sequence:

ip netns add crash
ip -n crash link add dummy1 type dummy
ip -n crash link set dummy1 up
ip -n crash -6 route add default dev dummy1
ip -n crash -6 rule add table main suppress_prefixlength 0
ip netns exec crash ping -f -c 1000 -W 1 1234::1 || true
ip -n crash -6 rule del table main suppress_prefixlength 0
ip -n crash link del dummy1
ip netns del crash

I submitted a patch for this upstream here:

https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=ca7a03c4175366a92cee0ccc4fec0038c3266e26

It's been backported to stable already. Update your kernel to 5.3.4
and things should work again for you.

Jason
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Re: Kernel panic on 5.3.1-arch1-1-ARCH

[Nico Schottelius]

Hey Jason,

thanks for the quick reply - I' ll upgrade as soon as a new package is
released and give a status update afterwards. Thanks for tracking it
down!

Best,

Nico

Jason A. Donenfeld <Jason@zx2c4.com> writes:

> This isn't WireGuard, actually. It's a line in wg-quick's bash that
> says `ip rule add ... suppress_prefix ...`.
>
> You can reproduce the kernel crash without WireGuard anywhere in the
> equation with this sequence:
>
> ip netns add crash
> ip -n crash link add dummy1 type dummy
> ip -n crash link set dummy1 up
> ip -n crash -6 route add default dev dummy1
> ip -n crash -6 rule add table main suppress_prefixlength 0
> ip netns exec crash ping -f -c 1000 -W 1 1234::1 || true
> ip -n crash -6 rule del table main suppress_prefixlength 0
> ip -n crash link del dummy1
> ip netns del crash
>
> I submitted a patch for this upstream here:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=ca7a03c4175366a92cee0ccc4fec0038c3266e26
>
> It's been backported to stable already. Update your kernel to 5.3.4
> and things should work again for you.
>
> Jason


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Re: Kernel panic on 5.3.1-arch1-1-ARCH

[Nico Schottelius]

... and just updated via the testing repo, everything green on 5.3.4.

On this system I see one error regarding the IPv4 fib table,
which might be due to IPv6 only usage:

[root@diamond ~]# wg-quick up wg0
[#] ip link add wg0 type wireguard
[#] wg setconf wg0 /dev/fd/63
[#] ip -6 address add 2a0a:e5c1:137::137/48 dev wg0
[#] ip link set mtu 1420 up dev wg0
Error: ipv4: FIB table does not exist.
Dump terminated
[#] wg set wg0 fwmark 51820
[#] ip -6 route add ::/0 dev wg0 table 51820
[#] ip -6 rule add not fwmark 51820 table 51820
[#] ip -6 rule add table main suppress_prefixlength 0
[root@diamond ~]# ip a sh dev wg0
5: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
    link/none
    inet6 2a0a:e5c1:137::137/48 scope global
       valid_lft forever preferred_lft forever
[root@diamond ~]# pacman -Q | grep wireguard
wireguard-dkms 0.0.20190913-1
wireguard-tools 0.0.20190913-1

As everything work[tm], would it be an option to rename it to a warning
instead?

Best,

Nico

Nico Schottelius <nico.schottelius@ungleich.ch> writes:

> Hey Jason,
>
> thanks for the quick reply - I' ll upgrade as soon as a new package is
> released and give a status update afterwards. Thanks for tracking it
> down!
>
> Best,
>
> Nico
>
> Jason A. Donenfeld <Jason@zx2c4.com> writes:
>
>> This isn't WireGuard, actually. It's a line in wg-quick's bash that
>> says `ip rule add ... suppress_prefix ...`.
>>
>> You can reproduce the kernel crash without WireGuard anywhere in the
>> equation with this sequence:
>>
>> ip netns add crash
>> ip -n crash link add dummy1 type dummy
>> ip -n crash link set dummy1 up
>> ip -n crash -6 route add default dev dummy1
>> ip -n crash -6 rule add table main suppress_prefixlength 0
>> ip netns exec crash ping -f -c 1000 -W 1 1234::1 || true
>> ip -n crash -6 rule del table main suppress_prefixlength 0
>> ip -n crash link del dummy1
>> ip netns del crash
>>
>> I submitted a patch for this upstream here:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=ca7a03c4175366a92cee0ccc4fec0038c3266e26
>>
>> It's been backported to stable already. Update your kernel to 5.3.4
>> and things should work again for you.
>>
>> Jason


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