net/smc: cancel event worker during device removal

commit ece0d7bd upstream.

During IB device removal, cancel the event worker before the device
structure is freed.

Fixes: a4cf0443 ("smc: introduce SMC as an IB-client")
Reported-by: syzbot+b297c6825752e7a07272@syzkaller.appspotmail.com
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/smc/smc_ib.c

@@ -561,6 +561,7 @@ static void smc_ib_remove_dev(struct ib_device *ibdev, void *client_data)
 	smc_pnet_remove_by_ibdev(smcibdev);
 	smc_ib_cleanup_per_ibdev(smcibdev);
 	ib_unregister_event_handler(&smcibdev->event_handler);
+	cancel_work_sync(&smcibdev->port_event_work);
 	kfree(smcibdev);
 }