CVE-2026-23393

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> bridge: cfm: Fix race condition in peer_mep deletion<br /> <br /> When a peer MEP is being deleted, cancel_delayed_work_sync() is called<br /> on ccm_rx_dwork before freeing. However, br_cfm_frame_rx() runs in<br /> softirq context under rcu_read_lock (without RTNL) and can re-schedule<br /> ccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync()<br /> returning and kfree_rcu() being called.<br /> <br /> The following is a simple race scenario:<br /> <br /> cpu0 cpu1<br /> <br /> mep_delete_implementation()<br /> cancel_delayed_work_sync(ccm_rx_dwork);<br /> br_cfm_frame_rx()<br /> // peer_mep still in hlist<br /> if (peer_mep-&gt;ccm_defect)<br /> ccm_rx_timer_start()<br /> queue_delayed_work(ccm_rx_dwork)<br /> hlist_del_rcu(&amp;peer_mep-&gt;head);<br /> kfree_rcu(peer_mep, rcu);<br /> ccm_rx_work_expired()<br /> // on freed peer_mep<br /> <br /> To prevent this, cancel_delayed_work_sync() is replaced with<br /> disable_delayed_work_sync() in both peer MEP deletion paths, so<br /> that subsequent queue_delayed_work() calls from br_cfm_frame_rx()<br /> are silently rejected.<br /> <br /> The cc_peer_disable() helper retains cancel_delayed_work_sync()<br /> because it is also used for the CC enable/disable toggle path where<br /> the work must remain re-schedulable.