wifi: cfg80211: cancel wiphy_work before freeing wiphy

JIRA: https://issues.redhat.com/browse/RHEL-79791
CVE: CVE-2025-21979

commit 72d5204
Author: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Date:   Thu Mar 6 12:37:59 2025 +0200

    wifi: cfg80211: cancel wiphy_work before freeing wiphy
    
    A wiphy_work can be queued from the moment the wiphy is allocated and
    initialized (i.e. wiphy_new_nm). When a wiphy_work is queued, the
    rdev::wiphy_work is getting queued.
    
    If wiphy_free is called before the rdev::wiphy_work had a chance to run,
    the wiphy memory will be freed, and then when it eventally gets to run
    it'll use invalid memory.
    
    Fix this by canceling the work before freeing the wiphy.
    
    Fixes: a3ee4dc ("wifi: cfg80211: add a work abstraction with special semantics")
    Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
    Reviewed-by: Johannes Berg <johannes.berg@intel.com>
    Link: https://patch.msgid.link/20250306123626.efd1d19f6e07.I48229f96f4067ef73f5b87302335e2fd750136c9@changeid
    Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>

Author: jtornosm

net/wireless/core.c

@@ -1194,6 +1194,13 @@ void cfg80211_dev_free(struct cfg80211_registered_device *rdev)
 {
 	struct cfg80211_internal_bss *scan, *tmp;
 	struct cfg80211_beacon_registration *reg, *treg;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rdev->wiphy_work_lock, flags);
+	WARN_ON(!list_empty(&rdev->wiphy_work_list));
+	spin_unlock_irqrestore(&rdev->wiphy_work_lock, flags);
+	cancel_work_sync(&rdev->wiphy_work);
+
 	rfkill_destroy(rdev->wiphy.rfkill);
 	list_for_each_entry_safe(reg, treg, &rdev->beacon_registrations, list) {
 		list_del(&reg->list);