net/smc: check for valid ib_client_data

In smc_ib_remove_dev() check if the provided ib device was actually
initialized for SMC before.

Reported-by: syzbot+84484ccebdd4e5451d91@syzkaller.appspotmail.com
Fixes: a4cf0443 ("smc: introduce SMC as an IB-client")
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/smc_ib.c

@@ -573,6 +573,8 @@ static void smc_ib_remove_dev(struct ib_device *ibdev, void *client_data)
 	struct smc_ib_device *smcibdev;
 
 	smcibdev = ib_get_client_data(ibdev, &smc_ib_client);
+	if (!smcibdev || smcibdev->ibdev != ibdev)
+		return;
 	ib_set_client_data(ibdev, &smc_ib_client, NULL);
 	spin_lock(&smc_ib_devices.lock);
 	list_del_init(&smcibdev->list); /* remove from smc_ib_devices */