panic: runtime error: invalid memory address or nil pointer dereference about k3s HOT 8 CLOSED

Yes, appears to be a bug in flannel - cc @manuelbuil - any reason we didn't bump flannel to 0.25.4 for this cycle?

IIRC 0.25.3 and 0.25.4 are mostly fixes for windows code. It seems the bug is in the flannel code in k3s which is not adapted to a change that happened around iptables

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The issue is not related to the Fix done in flannel that was done on the main.go file that it's not used on K3s. The issue is related to the fix that wasn't ported also on K3s flannel.go file.

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This is also broken in v1.29.6+k3s1. I was really hoping to get the fix for #9957 in there, but k3s doesn't even fire up because of this. Had to roll back to v1.29.5+k3s1.

How did this make it to stable? There must be situations where it doesn't crash in a loop?

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Yes, appears to be a bug in flannel - cc @manuelbuil - any reason we didn't bump flannel to 0.25.4 for this cycle?

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@kyrofa It only crashes when you use the embedded flannel with an ipv6 cluster-cidr and enable --flannel-ipv6-masq, which is disabled by default. We don't currently have any tests that cover this non-default configuration, but will be adding some in response to this regression.

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Ah ha, thank you @brandond, much appreciated.

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This morning I upgraded to v1.30.2-rc1+k3s2 which is working fine.
Thank you for fixing this 👍

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$ /var/lib/rancher/k3s/data/current/bin/flannel -V

CNI Plugin flannel version v1.4.0-flannel1+v0.25.4 (linux/amd64) commit HEAD built on 2024-07-18T00:33:12Z
CNI protocol versions supported: 0.1.0, 0.2.0, 0.3.0, 0.3.1, 0.4.0, 1.0.0

$ k3s -v

k3s version v1.30.3-rc1+k3s1 (086d9ca0)
go version go1.22.5

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