From: Ibrahim Hashimov Date: Tue, 21 Jul 2026 21:12:28 +0000 (+0200) Subject: mac802154: hold an interface reference across the scan worker X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=234e5e898b713bc0b3a631b6f002897f43d046c8;p=thirdparty%2Fkernel%2Flinux.git mac802154: hold an interface reference across the scan worker mac802154_scan_worker() captures the scanning sub-interface under RCU and then keeps dereferencing sdata->dev after rcu_read_unlock() and outside the rtnl -- in the failure traces, in mac802154_transmit_beacon_req() (skb->dev = sdata->dev), and in the end_scan cleanup. Nothing keeps that netdev alive across the worker iteration. A concurrent DEL_INTERFACE or PHY removal can unregister the interface once the worker drops the rtnl between its two drv_set_channel() sections. unregister_netdevice() frees the netdev asynchronously from netdev_run_todo() with the rtnl already dropped, so neither holding the rtnl nor the per-PHY IEEE802154_IS_SCANNING flag prevents a stale worker iteration from dereferencing the freed netdev -- a KASAN slab-use-after-free, reachable by racing TRIGGER_SCAN against DEL_INTERFACE (both CAP_NET_ADMIN). Pin the netdev with netdev_hold() while the RCU read lock is still held, and release it at every worker exit. Fixes: 57588c71177f ("mac802154: Handle passive scanning") Cc: stable@vger.kernel.org Signed-off-by: Ibrahim Hashimov Link: https://patch.msgid.link/20260721211228.34578-1-security@auditcode.ai Signed-off-by: Jakub Kicinski --- diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c index 300d4584533e..65089826ff59 100644 --- a/net/mac802154/scan.c +++ b/net/mac802154/scan.c @@ -179,6 +179,7 @@ void mac802154_scan_worker(struct work_struct *work) enum nl802154_scan_types scan_req_type; struct ieee802154_sub_if_data *sdata; unsigned int scan_duration = 0; + netdevice_tracker dev_tracker; struct wpan_phy *wpan_phy; u8 scan_req_duration; u8 page, channel; @@ -209,6 +210,14 @@ void mac802154_scan_worker(struct work_struct *work) return; } + /* + * sdata->dev is dereferenced below after rcu_read_unlock() and outside + * the rtnl, and a concurrent DEL_INTERFACE / PHY teardown can free it + * asynchronously from netdev_run_todo(). Pin it with a reference taken + * while the RCU read lock is still held, and drop it at every exit. + */ + netdev_hold(sdata->dev, &dev_tracker, GFP_ATOMIC); + wpan_phy = scan_req->wpan_phy; scan_req_type = scan_req->type; scan_req_duration = scan_req->duration; @@ -262,12 +271,14 @@ void mac802154_scan_worker(struct work_struct *work) "Scan page %u channel %u for %ums\n", page, channel, jiffies_to_msecs(scan_duration)); queue_delayed_work(local->mac_wq, &local->scan_work, scan_duration); + netdev_put(sdata->dev, &dev_tracker); return; end_scan: rtnl_lock(); mac802154_scan_cleanup_locked(local, sdata, false); rtnl_unlock(); + netdev_put(sdata->dev, &dev_tracker); } int mac802154_trigger_scan_locked(struct ieee802154_sub_if_data *sdata,