net: vlan: Avoid using BUG() in vlan_proto_idx()

While we should always make sure that we specify a valid VLAN protocol
to vlan_proto_idx(), killing the machine when an invalid value is
specified is too harsh and not helpful for debugging. All callers are
capable of dealing with an error returned by vlan_proto_idx() so check
the index value and propagate it accordingly.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/8021q/vlan.c

@@ -57,6 +57,9 @@ static int vlan_group_prealloc_vid(struct vlan_group *vg,
 	ASSERT_RTNL();
 
 	pidx  = vlan_proto_idx(vlan_proto);
+	if (pidx < 0)
+		return -EINVAL;
+
 	vidx  = vlan_id / VLAN_GROUP_ARRAY_PART_LEN;
 	array = vg->vlan_devices_arrays[pidx][vidx];
 	if (array != NULL)

net/8021q/vlan.h

@@ -36,16 +36,16 @@ struct vlan_info {
 	struct rcu_head		rcu;
 };
 
-static inline unsigned int vlan_proto_idx(__be16 proto)
+static inline int vlan_proto_idx(__be16 proto)
 {
 	switch (proto) {
 	case htons(ETH_P_8021Q):
 		return VLAN_PROTO_8021Q;
 	case htons(ETH_P_8021AD):
 		return VLAN_PROTO_8021AD;
 	default:
-		BUG();
-		return 0;
+		WARN(1, "invalid VLAN protocol: 0x%04x\n", ntohs(proto));
+		return -EINVAL;
 	}
 }
 
@@ -64,17 +64,24 @@ static inline struct net_device *vlan_group_get_device(struct vlan_group *vg,
 						       __be16 vlan_proto,
 						       u16 vlan_id)
 {
-	return __vlan_group_get_device(vg, vlan_proto_idx(vlan_proto), vlan_id);
+	int pidx = vlan_proto_idx(vlan_proto);
+
+	if (pidx < 0)
+		return NULL;
+
+	return __vlan_group_get_device(vg, pidx, vlan_id);
 }
 
 static inline void vlan_group_set_device(struct vlan_group *vg,
 					 __be16 vlan_proto, u16 vlan_id,
 					 struct net_device *dev)
 {
+	int pidx = vlan_proto_idx(vlan_proto);
 	struct net_device **array;
-	if (!vg)
+
+	if (!vg || pidx < 0)
 		return;
-	array = vg->vlan_devices_arrays[vlan_proto_idx(vlan_proto)]
+	array = vg->vlan_devices_arrays[pidx]
 				       [vlan_id / VLAN_GROUP_ARRAY_PART_LEN];
 	array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN] = dev;
 }