Merge branch 'net-smc-fixes-2021-11-24'

Karsten Graul says:

====================
net/smc: fixes 2021-11-24

Patch 1 from DaXing fixes a possible loop in smc_listen().
Patch 2 prevents a NULL pointer dereferencing while iterating
over the lower network devices.
====================

Link: https://lore.kernel.org/r/20211124123238.471429-1-kgraul@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

net/smc/af_smc.c

@@ -2134,8 +2134,10 @@ static int smc_listen(struct socket *sock, int backlog)
 	smc->clcsock->sk->sk_user_data =
 		(void *)((uintptr_t)smc | SK_USER_DATA_NOCOPY);
 	rc = kernel_listen(smc->clcsock, backlog);
-	if (rc)
+	if (rc) {
+		smc->clcsock->sk->sk_data_ready = smc->clcsk_data_ready;
 		goto out;
+	}
 	sk->sk_max_ack_backlog = backlog;
 	sk->sk_ack_backlog = 0;
 	sk->sk_state = SMC_LISTEN;

net/smc/smc_core.c

@@ -1672,14 +1672,26 @@ static void smc_link_down_work(struct work_struct *work)
 	mutex_unlock(&lgr->llc_conf_mutex);
 }
 
-/* Determine vlan of internal TCP socket.
- * @vlan_id: address to store the determined vlan id into
- */
+static int smc_vlan_by_tcpsk_walk(struct net_device *lower_dev,
+				  struct netdev_nested_priv *priv)
+{
+	unsigned short *vlan_id = (unsigned short *)priv->data;
+
+	if (is_vlan_dev(lower_dev)) {
+		*vlan_id = vlan_dev_vlan_id(lower_dev);
+		return 1;
+	}
+
+	return 0;
+}
+
+/* Determine vlan of internal TCP socket. */
 int smc_vlan_by_tcpsk(struct socket *clcsock, struct smc_init_info *ini)
 {
 	struct dst_entry *dst = sk_dst_get(clcsock->sk);
+	struct netdev_nested_priv priv;
 	struct net_device *ndev;
-	int i, nest_lvl, rc = 0;
+	int rc = 0;
 
 	ini->vlan_id = 0;
 	if (!dst) {
@@ -1697,20 +1709,9 @@ int smc_vlan_by_tcpsk(struct socket *clcsock, struct smc_init_info *ini)
 		goto out_rel;
 	}
 
+	priv.data = (void *)&ini->vlan_id;
 	rtnl_lock();
-	nest_lvl = ndev->lower_level;
-	for (i = 0; i < nest_lvl; i++) {
-		struct list_head *lower = &ndev->adj_list.lower;
-
-		if (list_empty(lower))
-			break;
-		lower = lower->next;
-		ndev = (struct net_device *)netdev_lower_get_next(ndev, &lower);
-		if (is_vlan_dev(ndev)) {
-			ini->vlan_id = vlan_dev_vlan_id(ndev);
-			break;
-		}
-	}
+	netdev_walk_all_lower_dev(ndev, smc_vlan_by_tcpsk_walk, &priv);
 	rtnl_unlock();
 
 out_rel: