CyberRota Analysis
AI-GeneratedThe Linux kernel's netfilter component is vulnerable due to improper ordering in the unregistration of loggers, which can lead to a race condition allowing a sysctl or netlink writer to rebind a stale logger pointer. This can result in potential memory corruption during logging operations, impacting system stability and security. System administrators and developers managing Linux kernel environments, particularly those utilizing netfilter for network logging, should prioritize applying the fix to mitigate these risks.
Original NVD Description
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.