In the Linux kernel, the following vulnerability has been resolved:

ip6: vti: Use ip6_tnl.net in vti6_changelink().

ip netns add ns1
ip netns add ns2
ip -n ns1 link add vti6_test type vti6 remote ::1 local ::2 key 7
ip -n ns1 link set vti6_test netns ns2
ip -n ns2 link set vti6_test type vti6 remote ::3 local ::4 key 9
ip netns del ns2
ip netns del ns1
[  132.495484] ------------[ cut here ]------------
[  132.497609] kernel BUG at net/core/dev.c:12376!

Commit 61220ab34948 ("vti6: Enable namespace changing") dropped
NETIF_F_NETNS_LOCAL from vti6 devices. A vti6 tunnel can then
move through IFLA_NET_NS_FD. After the move dev_net(dev) points
at the new netns while t->net stays at the creation netns.

vti6_changelink() and vti6_update() still use dev_net(dev) and
dev_net(t->dev). They unlink from one per netns hash and relink
into another. The creation netns is left with a stale entry.
cleanup_net() of that netns later walks freed memory.

Reachable from an unprivileged user namespace (unshare --user
--map-root-user --net). Cross tenant scope on container hosts.

https://git.kernel.org/stable/c/0cdce7618464f7fb06f461e8f4ad575cb1d570f4

https://git.kernel.org/stable/c/11b326fb0a374f4654f9be22d0f0f7abd9f7d3fe

https://git.kernel.org/stable/c/225b467e3b631f38be22e4b38062a1fed02fdd21

https://git.kernel.org/stable/c/d9c5eecdb3c740e65038651db7c686b10d76d1bc

https://git.kernel.org/stable/c/ee1778ba0f5cb53be771f97017d01eb356c797bf

https://git.kernel.org/stable/c/f1e89a943ee574d0f2f16246eb3f2d7330fdeb03

https://git.kernel.org/stable/c/f5c68875e25f331e497ddfbe81e2d8163a87f136

https://git.kernel.org/stable/c/fc32be9ac2788524c6b24efd681cce7a6e731a92

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