Package: linux-image-6.1.0-43-amd64
Version: 6.1.162-1
Severity: important
Tags: upstream
Hello,
The ip6_tunnel kernel module is broken in linux-image-6.1.0-43-amd64
(upstream 6.1.162). IPv6 tunnels (mode "any") fail to encapsulate or
transmit any packets.
WORKING CONFIGURATION:
- Kernel: 6.1.0-37-amd64 (upstream 6.1.140)
- Tunnel works correctly with identical configuration
BROKEN CONFIGURATION:
- Kernel: 6.1.0-43-amd64 (upstream 6.1.162)
- Same tunnel configuration fails completely
REPRODUCTION STEPS:
1. Create IPv6 tunnel with mode "any":
ip link add tun0 type ip6tnl mode any \
remote 2001:db8::2 \
local 2001:db8::1 \
encaplimit 4
ip addr add 192.0.2.1/30 dev tun0
ip addr add 2001:db8:1::1/126 dev tun0
ip link set tun0 up mtu 1500
2. Send traffic through tunnel:
ping -c 3 -I tun0 192.0.2.2
3. Monitor physical interface:
tcpdump -i eth0 -nn 'ip6 and host 2001:db8::2'
EXPECTED BEHAVIOR (kernel 6.1.0-37):
- tcpdump shows encapsulated packets with protocol 60 (DSTOPT) or 4 (IPIP)
- Tunnel traffic flows successfully
ACTUAL BEHAVIOR (kernel 6.1.0-43):
- tcpdump captures ZERO packets
- TX counter increments on tunnel interface but packets disappear in
kernel
- RX packets show errors
EVIDENCE - Side-by-side comparison:
Kernel 6.1.0-37 (WORKING):
Protocol 60 (DSTOPT) packets visible on wire
Encapsulation functioning correctly
Kernel 6.1.0-43 (BROKEN):
0 packets captured
No packets transmitted to physical interface
SYSTEM INFORMATION:
- Debian version: 12 (bookworm)
- Architecture: amd64
- Broken kernel: 6.1.0-43-amd64 (6.1.162-1)
- Working kernel: 6.1.0-37-amd64 (6.1.140-1)
- Boot parameters tested: default and mitigations=off (both fail)
IMPACT:
- All IPv6 tunnels using ip6tnl module are affected
- Workaround: downgrade to 6.1.0-37
ADDITIONAL NOTES:
- Issue persists regardless of tunnel parameters (MTU, encaplimit,
offloads)
- Module parameter changes have no effect
- Issue affects both encapsulation (TX) and decapsulation (RX)
- No relevant errors in dmesg or kernel logs
Could you please investigate this regression? Is there any additional
debugging information or testing I can provide to help identify the root
cause?
Would additional debugging output be helpful? I can provide kernel
logs, strace output, or test patches if needed.
--
[image: Hostinger Logo]
Network Operations Center
*NOC *| Hostinger Global
*E: *[email protected] <[email protected]>
*W: *www.hostinger.com
*A: *Global HQ, Jonavos g. 60c, Kaunas 44192
[image: Facebook Icon] <https://www.facebook.com/hostinger/> [image:
Instagram Icon] <https://www.instagram.com/hostinger_global/> [image:
Twitter Icon] <https://twitter.com/Hostinger> [image: Youtube Icon]
<https://www.youtube.com/channel/UC4UDct7xQd0Ng6G_eMHnA1Q>
[image: Linkedin Icon]
<https://www.linkedin.com/company/hostinger-international/>
--
This
message and its attachments may contain privileged and confidential
information. If you are not the intended recipient, do not use, copy, or
disclose this information. Please notify the sender and permanently
delete
the message from your system.
