CVE-2026-97608

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

netfilter: nf_log: unregister loggers before per-net teardown

nf_log_syslog and nfnetlink_log unregister their per-network namespace

operations before unregistering their global logger backends. This

leaves a window where a sysctl or netlink writer can rebind the still-

registered logger after the per-net pre-exit callback cleared the old

selection.

The race looks like this:

CPU 0 CPU 1

---- ----

unregister_pernet_subsys()

nf_log_unset(net, logger)

net->nf.nf_loggers[pf] = NULL

lock nf_log_mutex

find logger in loggers[][]

net->nf.nf_loggers[pf] = logger

unlock nf_log_mutex

nf_log_unregister(logger)

lock nf_log_mutex

loggers[pf][type] = NULL

unlock nf_log_mutex

synchronize_rcu()

module exit returns

module core frees backend memory

Later, a sysctl read or packet logging operation can dereference the

stale per-net logger pointer.

Fix this by unregistering the global logger backends before tearing down

per-net state. Once the global registrations are gone, later writers can

no longer rebind the logger. unregister_pernet_subsys() already waits

for an RCU grace period after the pre-exit callback clears the per-net

selection, while nf_log_unregister() continues to cover readers of the

global logger table.

Apply this ordering fix to both nf_log backends that combine per-net

teardown with global logger registration.