6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Johannes Berg <johannes.berg@xxxxxxxxx>
commit d5fee261dfd9e17b08b1df8471ac5d5736070917 upstream.
When we free wdev->cqm_config when unregistering, we also
need to clear out the pointer since the same wdev/netdev
may get re-registered in another network namespace, then
destroyed later, running this code again, which results in
a double-free.
Reported-by: syzbot+36218cddfd84b5cc263e@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 37c20b2effe9 ("wifi: cfg80211: fix cqm_config access race")
Cc: stable@xxxxxxxxxxxxxxx
Link: https://patch.msgid.link/20241022161742.7c34b2037726.I121b9cdb7eb180802eafc90b493522950d57ee18@changeid
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/wireless/core.c | 1 +
1 file changed, 1 insertion(+)
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1233,6 +1233,7 @@ static void _cfg80211_unregister_wdev(st
/* deleted from the list, so can't be found from nl80211 any more */
cqm_config = rcu_access_pointer(wdev->cqm_config);
kfree_rcu(cqm_config, rcu_head);
+ RCU_INIT_POINTER(wdev->cqm_config, NULL);
/*
* Ensure that all events have been processed and
