net: caif: add proper error handling

caif_enroll_dev() can fail in some cases. Ingnoring
these cases can lead to memory leak due to not assigning
link_support pointer to anywhere.

Fixes: 7c18d2205ea7 ("caif: Restructure how link caif link layer enroll")
Cc: [e-mail]
Signed-off-by: Pavel Skripkin <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/caif/caif_dev.h

···
  * The link_support layer is used to add any Link Layer specific
  * framing.
  */
-void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
+int caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 			struct cflayer *link_support, int head_room,
 			struct cflayer **layer, int (**rcv_func)(
 				struct sk_buff *, struct net_device *,

include/net/caif/cfcnfg.h

···
  * @fcs:	Specify if checksum is used in CAIF Framing Layer.
  * @head_room:	Head space needed by link specific protocol.
  */
-void
+int
 cfcnfg_add_phy_layer(struct cfcnfg *cnfg,
 		     struct net_device *dev, struct cflayer *phy_layer,
 		     enum cfcnfg_phy_preference pref,

net/caif/caif_dev.c

···
 	caifd_put(caifd);
 }
 
-void caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
+int caif_enroll_dev(struct net_device *dev, struct caif_dev_common *caifdev,
 		     struct cflayer *link_support, int head_room,
 		     struct cflayer **layer,
 		     int (**rcv_func)(struct sk_buff *, struct net_device *,
···
 	enum cfcnfg_phy_preference pref;
 	struct cfcnfg *cfg = get_cfcnfg(dev_net(dev));
 	struct caif_device_entry_list *caifdevs;
+	int res;
 
 	caifdevs = caif_device_list(dev_net(dev));
 	caifd = caif_device_alloc(dev);
 	if (!caifd)
-		return;
+		return -ENOMEM;
 	*layer = &caifd->layer;
 	spin_lock_init(&caifd->flow_lock);
 
···
 	strlcpy(caifd->layer.name, dev->name,
 		sizeof(caifd->layer.name));
 	caifd->layer.transmit = transmit;
-	cfcnfg_add_phy_layer(cfg,
+	res = cfcnfg_add_phy_layer(cfg,
 				dev,
 				&caifd->layer,
 				pref,
···
 	mutex_unlock(&caifdevs->lock);
 	if (rcv_func)
 		*rcv_func = receive;
+	return res;
 }
 EXPORT_SYMBOL(caif_enroll_dev);
 

net/caif/cfcnfg.c

···
 	rcu_read_unlock();
 }
 
-void
+int
 cfcnfg_add_phy_layer(struct cfcnfg *cnfg,
 		     struct net_device *dev, struct cflayer *phy_layer,
 		     enum cfcnfg_phy_preference pref,
···
 {
 	struct cflayer *frml;
 	struct cfcnfg_phyinfo *phyinfo = NULL;
-	int i;
+	int i, res = 0;
 	u8 phyid;
 
 	mutex_lock(&cnfg->lock);
···
 			goto got_phyid;
 	}
 	pr_warn("Too many CAIF Link Layers (max 6)\n");
+	res = -EEXIST;
 	goto out;
 
 got_phyid:
 	phyinfo = kzalloc(sizeof(struct cfcnfg_phyinfo), GFP_ATOMIC);
-	if (!phyinfo)
+	if (!phyinfo) {
+		res = -ENOMEM;
 		goto out_err;
+	}
 
 	phy_layer->id = phyid;
 	phyinfo->pref = pref;
···
 
 	frml = cffrml_create(phyid, fcs);
 
-	if (!frml)
+	if (!frml) {
+		res = -ENOMEM;
 		goto out_err;
+	}
 	phyinfo->frm_layer = frml;
 	layer_set_up(frml, cnfg->mux);
 
···
 	list_add_rcu(&phyinfo->node, &cnfg->phys);
 out:
 	mutex_unlock(&cnfg->lock);
-	return;
+	return res;
 
 out_err:
 	kfree(phyinfo);
 	mutex_unlock(&cnfg->lock);
+	return res;
 }
 EXPORT_SYMBOL(cfcnfg_add_phy_layer);