Affected: Linux

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

wifi: cfg80211: cancel sched scan results work on unregister

cfg80211_sched_scan_results() can queue rdev->sched_scan_res_wk from a driver result notification while a scheduled scan request is present. The work callback recovers the containing cfg80211_registered_device and then locks the wiphy and walks the scheduled-scan request list.

wiphy_unregister() already makes the wiphy unreachable and drains rdev work items before cfg80211_dev_free() can release the object, but it does not drain sched_scan_res_wk. A queued or running result work item can therefore cross the unregister/free boundary and access freed rdev state.

The buggy scenario involves two paths, with each column showing the order within that path:

scheduled-scan result path: unregister/free path: 1. cfg80211_sched_scan_results() 1. interface teardown stops and queues rdev->sched_scan_res_wk. removes the scheduled scan request. 2. cfg80211_wq starts the work 2. wiphy_unregister() drains other item and recovers rdev. rdev work items. 3. The worker locks rdev->wiphy 3. cfg80211_dev_free() destroys and and walks rdev state. frees rdev.

Cancel sched_scan_res_wk in wiphy_unregister() alongside the other rdev work items. cancel_work_sync() removes a pending result notification and waits for an already running callback, so cfg80211_dev_free() cannot free rdev while this work item is still active.…