CVE-2023-52509

In the Linux kernel, the following vulnerability has been resolved: ravb:
Fix use-after-free issue in ravb_tx_timeout_work() The ravb_stop() should
call cancel_work_sync(). Otherwise, ravb_tx_timeout_work() is possible to
use the freed priv after ravb_remove() was called like below: CPU0 CPU1
ravb_tx_timeout() ravb_remove() unregister_netdev() free_netdev(ndev) //
free priv ravb_tx_timeout_work() // use priv unregister_netdev() will call
.ndo_stop() so that ravb_stop() is called. And, after phy_stop() is called,
netif_carrier_off() is also called. So that .ndo_tx_timeout() will not be
called after phy_stop().