Feat/support ip6tnlmtu fix the issue that cause lo refcount leak #1
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@moycat Hi, that will be appreciated if you have time to review this PR |
moycat
requested changes
Apr 2, 2025
I’ve made the requested changes and updated the PR accordingly. Please let me know if you need any further adjustments. |
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LGTM. Thanks a lot! |
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We recently encountered a kernel bug similar to the one described in this thread. The root cause of the issue is that Dst objects get leaked in ip6_negative_advice() when this function is executed for an expired IPv6 route located in the exception table but the trigger of this issue was the router responds with an ICMP “Message Too Long” message, which triggers an MTU change. This, in turn, causes a route entry to be added to the route cache, eventually leading to the kernel bug mentioned above.
This problem occurs when communicating across hosts because the MTU of the ip6tnl interface is 1450, which is smaller than the MTU of the NIC. As a result, the MTU mismatch causes the IP is cached and trigger the subtle bug
The purpose of this PR is to introduce a new configuration option that allows setting a custom MTU for the ip6tnl interface to prevent this issue.