CVE-2026-97608

Summary

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.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/eaec35fae8f2052c1878a5c7cc7699d8357d79f2
• https://git.kernel.org/stable/c/64803ba0a05791cf9ca874466480e4c4cadaf7ab
• https://git.kernel.org/stable/c/dce24f3a146948595bb1b86347f31e20b4975daa
• https://git.kernel.org/stable/c/2c018cc4842c33f0c732962e2ab58635e8ae5823

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