Drivers: hv: check vmbus_device_create() return value in vmbus_process_offer()

vmbus_device_create() result is not being checked in vmbus_process_offer() and
it can fail if kzalloc() fails. Add the check and do minor cleanup to avoid
additional duplication of "free_channel(); return;" block.
Reported-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/channel_mgmt.c

@@ -341,11 +341,10 @@ static void vmbus_process_offer(struct work_struct *work)
 			if (channel->sc_creation_callback != NULL)
 				channel->sc_creation_callback(newchannel);
 
-			return;
+			goto out;
 		}
 
-		free_channel(newchannel);
-		return;
+		goto err_free_chan;
 	}
 
 	/*
@@ -364,6 +363,8 @@ static void vmbus_process_offer(struct work_struct *work)
 		&newchannel->offermsg.offer.if_type,
 		&newchannel->offermsg.offer.if_instance,
 		newchannel);
+	if (!newchannel->device_obj)
+		goto err_free_chan;
 
 	/*
 	 * Add the new device to the bus. This will kick off device-driver
@@ -379,9 +380,12 @@ static void vmbus_process_offer(struct work_struct *work)
 		list_del(&newchannel->listentry);
 		spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
 		kfree(newchannel->device_obj);
-
-		free_channel(newchannel);
+		goto err_free_chan;
 	}
+out:
+	return;
+err_free_chan:
+	free_channel(newchannel);
 }
 
 enum {