ip6gre driver does not hold device reference

This bug is awaiting verification that the linux/4.15.0-177.186 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-bionic' to 'verification-done-bionic'. If the problem still exists, change the tag 'verification-needed-bionic' to 'verification-failed-bionic'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

Fails with the kernel in -updates, 4.15.0-176.

Works with kernel in -proposed, 4.15.0-177.

ubuntu@bionic:~$ uname -r
4.15.0-177-generic
ubuntu@bionic:~$ sudo modprobe ip6_gre
ubuntu@bionic:~$ unshare -Urn true
ubuntu@bionic:~$ unshare -Urn true
ubuntu@bionic:~$ unshare -Urn true
ubuntu@bionic:~$ dmesg | tail -2
[ 14.212867] gre: GRE over IPv4 demultiplexor driver
[ 14.218947] ip6_gre: GRE over IPv6 tunneling driver
ubuntu@bionic:~$

This bug was fixed in the package linux - 4.15.0-177.186

---------------
linux (4.15.0-177.186) bionic; urgency=medium

  * bionic/linux: 4.15.0-177.186 -proposed tracker (LP: #1969083)

  * Bionic update: upstream stable patchset 2022-04-13 (LP: #1968932)
    - cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug
    - vhost/vsock: don't check owner in vhost_vsock_stop() while releasing
    - parisc/unaligned: Fix fldd and fstd unaligned handlers on 32-bit kernel
    - parisc/unaligned: Fix ldw() and stw() unalignment handlers
    - sr9700: sanity check for packet length
    - USB: zaurus: support another broken Zaurus
    - ping: remove pr_err from ping_lookup
    - net: __pskb_pull_tail() & pskb_carve_frag_list() drop_monitor friends
    - gso: do not skip outer ip header in case of ipip and net_failover
    - openvswitch: Fix setting ipv6 fields causing hw csum failure
    - drm/edid: Always set RGB444
    - net/mlx5e: Fix wrong return value on ioctl EEPROM query failure
    - configfs: fix a race in configfs_{,un}register_subsystem()
    - RDMA/ib_srp: Fix a deadlock
    - iio: adc: men_z188_adc: Fix a resource leak in an error handling path
    - ata: pata_hpt37x: disable primary channel on HPT371
    - Revert "USB: serial: ch341: add new Product ID for CH341A"
    - usb: gadget: rndis: add spinlock for rndis response list
    - tracefs: Set the group ownership in apply_options() not parse_options()
    - USB: serial: option: add support for DW5829e
    - USB: serial: option: add Telit LE910R1 compositions
    - usb: dwc3: gadget: Let the interrupt handler disable bottom halves.
    - xhci: re-initialize the HC during resume if HCE was set
    - xhci: Prevent futile URB re-submissions due to incorrect return value.
    - tty: n_gsm: fix encoding of control signal octet bit DV
    - tty: n_gsm: fix proper link termination after failed open
    - Revert "drm/nouveau/pmu/gm200-: avoid touching PMU outside of
      DEVINIT/PREOS/ACR"
    - memblock: use kfree() to release kmalloced memblock regions
    - fget: clarify and improve __fget_files() implementation
    - gpio: tegra186: Fix chip_data type confusion
    - tracing: Have traceon and traceoff trigger honor the instance
    - mac80211_hwsim: report NOACK frames in tx_status
    - mac80211_hwsim: initialize ieee80211_tx_info at hw_scan_work
    - i2c: bcm2835: Avoid clock stretching timeouts
    - Input: clear BTN_RIGHT/MIDDLE on buttonpads
    - cifs: fix double free race when mount fails in cifs_get_root()
    - dmaengine: shdma: Fix runtime PM imbalance on error
    - i2c: cadence: allow COMPILE_TEST
    - i2c: qup: allow COMPILE_TEST
    - net: usb: cdc_mbim: avoid altsetting toggling for Telit FN990
    - usb: gadget: don't release an existing dev->buf
    - usb: gadget: clear related members when goto fail
    - ata: pata_hpt37x: fix PCI clock detection
    - ALSA: intel_hdmi: Fix reference to PCM buffer address
    - ASoC: ops: Shift tested values in snd_soc_put_volsw() by +min
    - xfrm: fix MTU regression
    - netfilter: fix use-after-free in __nf_register_net_hook()
    - xfrm: enforce validity of offload input flags
    - netfilter: nf_queue: don't assume sk ...