In the Linux kernel, the following vulnerability has been resolved: bridge: cfm: Fix race condition in peer_mep deletion When a peer MEP is being deleted, cancel_delayed_work_sync() is called on ccm_rx_dwork before freeing. However, br_cfm_frame_rx() runs in softirq context under rcu_read_lock (without RTNL) and can re-schedule ccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync() returning and kfree_rcu() being called. The following is a simple race scenario: cpu0 cpu1 mep_delete_implementation() cancel_delayed_work_sync(ccm_rx_dwork); br_cfm_frame_rx() // peer_mep still in hlist if (peer_mep->ccm_defect) ccm_rx_timer_start() queue_delayed_work(ccm_rx_dwork) hlist_del_rcu(&peer_mep->head); kfree_rcu(peer_mep, rcu); ccm_rx_work_expired() // on freed peer_mep To prevent this, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync() in both peer MEP deletion paths, so that subsequent queue_delayed_work() calls from br_cfm_frame_rx() are silently rejected. The cc_peer_disable() helper retains cancel_delayed_work_sync() because it is also used for the CC enable/disable toggle path where the work must remain re-schedulable.
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | dc32cbb3dbd7da38c700d6e0fc6354df24920525, dc32cbb3dbd7da38c700d6e0fc6354df24920525, dc32cbb3dbd7da38c700d6e0fc6354df24920525, dc32cbb3dbd7da38c700d6e0fc6354df24920525, 5.11, 6.12.77, 6.18.19, 6.19.9, 7.0-rc4 |
Updated affected versions to include 6.12.77, 6.18.19, 6.19.9, and 7.0-rc4, changed severity to CRITICAL, and noted that no exploit is available.
Initial creation
