In the Linux kernel, the following vulnerability has been resolved: wifi: cfg80211: use wiphy work for socket owner autodisconnect nl80211_netlink_notify() walks the cfg80211 wireless device list when a NETLINK_GENERIC socket is releas…

Overview

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

wifi: cfg80211: use wiphy work for socket owner autodisconnect

nl80211_netlink_notify() walks the cfg80211 wireless device list when a NETLINK_GENERIC socket is released. If the socket owns a connection, the notifier queues the embedded wdev->disconnect_wk work item.

That work is a plain work_struct today. NETDEV_GOING_DOWN cancels it, but a NETLINK_URELEASE notifier that already observed conn_owner_nlportid can queue it after that cancel returns. _cfg80211_unregister_wdev() then removes the wdev from the list and waits for RCU readers, but synchronize_net() does not drain work queued by such a reader.

Make the autodisconnect work a wiphy_work instead. The callback already needs the wiphy mutex, and wiphy_work runs under that mutex. This lets teardown cancel pending autodisconnect work while holding the mutex, without a cancel_work_sync() vs. worker locking concern.

Also cancel the wiphy work after list_del_rcu() and synchronize_net(). Any NETLINK_URELEASE notifier that had already reached the wdev list has then either queued the work and it is removed, or can no longer find the wdev.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.