CVE-2026-46120

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

ip6_gre: Use cached t->net in ip6erspan_changelink().

After commit 5e72ce3e3980 ("net: ipv6: Use link netns in newlink() of

rtnl_link_ops"), ip6erspan_newlink() correctly resolves the per-netns

ip6gre hash via link_net. ip6erspan_changelink() was not converted in

that series and still uses dev_net(dev), which diverges from the

device's creation netns after IFLA_NET_NS_FD migration.

This re-inserts the tunnel into the wrong per-netns hash. The

original netns keeps a stale entry. When that netns is later

destroyed, ip6gre_exit_rtnl_net() walks the stale entry, producing a

slab-use-after-free reported by KASAN, followed by a kernel BUG at

net/core/dev.c (LIST_POISON1) in unregister_netdevice_many_notify().

Reachable from an unprivileged user namespace (unshare --user

--map-root-user --net).

ip6gre_changelink() earlier in the same file already uses the cached

t->net; only ip6erspan_changelink() has the wrong shape.