mac802154: fix netdev use-after-free in beacon worker

mac802154_beacon_worker() reads local->beacon_req under RCU and derives
the sub-interface from the request, but then drops the RCU read lock and
continues to use both sdata and the embedded wpan_dev.

mac802154_stop_beacons_locked() cancels only pending beacon work, clears
local->beacon_req and frees the request.  A beacon worker that is already
running can therefore continue after interface teardown and dereference
the freed netdev private area.

The scan worker already pins the netdev before leaving RCU.  Apply the
same lifetime rule to the beacon worker: take a netdev reference while
the request is still protected by RCU, and release it on all paths that
continue after the reference is acquired.

Fixes: 3accf4762734 ("mac802154: Handle basic beaconing")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Signed-off-by: Zihan Xi <zihanx@nebusec.ai>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://patch.msgid.link/e9a3909c7a6281967961773ca841e860b8ecf40e.1785596603.git.zihanx@nebusec.ai
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c
index 65089826ff59725766fa5237872a80029eb566f7..005338f89b75e1f3348a7eae4c4722f8e5d21267 100644 (file)
--- a/net/mac802154/scan.c
+++ b/net/mac802154/scan.c
@@ -415,6 +415,7 @@ void mac802154_beacon_worker(struct work_struct *work)
                container_of(work, struct ieee802154_local, beacon_work.work);
        struct cfg802154_beacon_request *beacon_req;
        struct ieee802154_sub_if_data *sdata;
+       netdevice_tracker dev_tracker;
        struct wpan_dev *wpan_dev;
        u8 interval;
        int ret;
@@ -427,12 +428,14 @@ void mac802154_beacon_worker(struct work_struct *work)
        }
 
        sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(beacon_req->wpan_dev);
+       netdev_hold(sdata->dev, &dev_tracker, GFP_ATOMIC);
 
        /* Wait an arbitrary amount of time in case we cannot use the device */
        if (local->suspended || !ieee802154_sdata_running(sdata)) {
                rcu_read_unlock();
                queue_delayed_work(local->mac_wq, &local->beacon_work,
                                   msecs_to_jiffies(1000));
+               netdev_put(sdata->dev, &dev_tracker);
                return;
        }
 
@@ -450,6 +453,7 @@ void mac802154_beacon_worker(struct work_struct *work)
        if (interval < IEEE802154_ACTIVE_SCAN_DURATION)
                queue_delayed_work(local->mac_wq, &local->beacon_work,
                                   local->beacon_interval);
+       netdev_put(sdata->dev, &dev_tracker);
 }
 
 int mac802154_stop_beacons_locked(struct ieee802154_local *local,