In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: double hook unregistration in netns path
_nftreleasehooks() is called from prenetns exit path which unregisters the hooks, then the NETDEV_UNREGISTER event is triggered which unregisters the hooks again.
[ 565.221461] WARNING: CPU: 18 PID: 193 at net/netfilter/core.c:495 nfunregisternethook+0x247/0x270 [...] [ 565.246890] CPU: 18 PID: 193 Comm: kworker/u64:1 Tainted: G E 5.18.0-rc7+ #27 [ 565.253682] Workqueue: netns cleanupnet [ 565.257059] RIP: 0010:nfunregisternethook+0x247/0x270 [...] [ 565.297120] Call Trace: [ 565.300900] <TASK> [ 565.304683] nftablesflowtableevent+0x16a/0x220 [nftables] [ 565.308518] rawnotifiercallchain+0x63/0x80 [ 565.312386] unregisternetdevicemany+0x54f/0xb50
Unregister and destroy netdev hook from netns preexit via kfreercu so the NETDEV_UNREGISTER path see unregistered hooks.