Source: linux
Version: 4.19.118-2
Severity: important
Tags: ipv6 upstream fixed-upstream

IPv6 connectivity (and other network protocols relying on multicast) are
broken when using a Dell D6000 USB-C dock.
Quoting Miguel Rodríguez that filed the equivalent bug in ubuntu:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1779173:

"Dell D6000 exposes a CDC_NCM device for Ethernet traffic. However,
multicast Ethernet traffic is not processed making IPv6 not functional.
Other services, like mDNS used for LAN service discovery are also
hindered.

The actual reason is that CDC_NCM driver was not processing requests to
filter (admit) multicast traffic. I provide two patches to the linux
kernel that admit all Ethernet multicast traffic whenever a multicast
group is being joined.

The solution is not optimal, as it makes the system receive more traffic
than that strictly needed, but otherwise this only happens when the
computer is connected to a dock and thus is running on AC power. I
believe it is not worth the hassle to join only the requested groups.
This is the same that is done in the CDN_ETHER driver."

The patches proposed by Miguel Rodríguez have been merged upstream, and
are part of 5.9-rc1 now. C.f. commits:
37a2ebdd9e597ae1a0270ac747883ea8f6f767b6
e10dcb1b6ba714243ad5a35a11b91cc14103a9a9
e506addeff844237d60545ef4f6141de21471caf
0226009ce0f6089f9b31211f7a2703cf9a327a01

Cheers,

 -- Santiago

-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable'), (500, 
'oldstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.5.0-2-amd64 (SMP w/8 CPU threads)
Kernel taint flags: TAINT_WARN, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=es_CO.UTF-8, LC_CTYPE=es_CO.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

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