Fix StackOverflow exception when NewtonsoftJsonSerializer tries t…

…o deserialize a `JObject` inside an `object` field (#6503)

* Reproduction for  #6502

* Fix JObject inside object property/field overflow

---------

Co-authored-by: Aaron Stannard <aaron@petabridge.com>

src/core/Akka.Tests/Serialization/SerializationSpec.cs

@@ -7,6 +7,7 @@
 
 using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using System.IO;
 using System.Reflection;
 using System.Runtime.Serialization;
@@ -21,6 +22,7 @@
 using Akka.Util;
 using Akka.Util.Reflection;
 using FluentAssertions;
+using Newtonsoft.Json.Linq;
 using Xunit;
 
 namespace Akka.Tests.Serialization
@@ -608,6 +610,60 @@ public void Missing_custom_serializer_id_should_append_help_message()
                 .Where(ex => ex.Message.Contains("Serializer Id [101] is not one of the internal Akka.NET serializer."));
         }
 
+        [Fact(DisplayName = "Should be able to serialize object property with JObject value")]
+        public void ObjectPropertyJObjectTest()
+        {
+            var serializer = (NewtonSoftJsonSerializer) Sys.Serialization.FindSerializerForType(typeof(object));
+            var obj = JObject.FromObject(new
+            {
+                FormattedMessage = "We are apple 20 points above value 10.01 ms",
+                Message = "We are {0} {1} points above value {2} ms",
+                Parameters = new List<object> { "apple", 20, 10.01F, 50L, (decimal) 9.9 },
+                MessageType = 200
+            });
+            var instance = new ObjectTestClass { MyObject = obj};
+
+            var serialized = serializer.ToBinary(instance);
+
+            // Stack overflowed in the original bug
+            var deserialized = serializer.FromBinary<ObjectTestClass>(serialized);
+            deserialized.MyObject.Should().BeOfType<JObject>();
+            var jObj = (JObject) deserialized.MyObject;
+
+            ((JValue)jObj["FormattedMessage"])!.Value.Should().Be("We are apple 20 points above value 10.01 ms");
+            ((JValue)jObj["Message"])!.Value.Should().Be("We are {0} {1} points above value {2} ms");
+            var arr = ((JArray)jObj["Parameters"]);
+            ((JValue)arr![0]).Value.Should().Be("apple");
+            ((JValue)arr[1]).Value.Should().BeOfType<int>();
+            ((JValue)arr[1]).Value.Should().Be(20);
+            ((JValue)arr[2]).Value.Should().BeOfType<float>();
+            ((JValue)arr[2]).Value.Should().Be(10.01F);
+            ((JValue)arr[3]).Value.Should().BeOfType<long>();
+            ((JValue)arr[3]).Value.Should().Be(50L);
+            ((JValue)arr[4]).Value.Should().BeOfType<decimal>();
+            ((JValue)arr[4]).Value.Should().Be((decimal)9.9);
+            ((JValue)jObj["MessageType"])!.Value.Should().Be(200);
+        }
+
+        [Fact(DisplayName = "Should be able to serialize object property with anonymous type value")]
+        public void ObjectPropertyObjectTest()
+        {
+            var serializer = (NewtonSoftJsonSerializer) Sys.Serialization.FindSerializerForType(typeof(object));
+            var obj = new
+            {
+                FormattedMessage = "We are apple 20 points above value 10.01 ms",
+                Message = "We are {0} {1} points above value {2} ms",
+                Parameters = new List<object> { "apple", 20, 10.01F, 50L, (decimal) 9.9 },
+                MessageType = 200
+            };
+            var instance = new ObjectTestClass { MyObject = obj};
+
+            var serialized = serializer.ToBinary(instance);
+
+            var deserialized = serializer.FromBinary<ObjectTestClass>(serialized);
+            deserialized.MyObject.Should().BeEquivalentTo(obj);
+        }
+
         public SerializationSpec():base(GetConfig())
         {
         }
@@ -708,6 +764,11 @@ public sealed class ChildClass
                 public string Value { get; set; }
             }
         }
+
+        public sealed class ObjectTestClass
+        {
+            public object MyObject { get; set; }
+        }
     }
 }
 

src/core/Akka/Serialization/NewtonSoftJsonSerializer.cs

@@ -331,8 +331,7 @@ public override object FromBinary(byte[] bytes, Type type)
 
         private static object TranslateSurrogate(object deserializedValue, NewtonSoftJsonSerializer parent, Type type)
         {
-            var j = deserializedValue as JObject;
-            if (j != null)
+            if (deserializedValue is JObject j)
             {
                 //The JObject represents a special akka.net wrapper for primitives (int,float,decimal) to preserve correct type when deserializing
                 if (j["$"] != null)
@@ -341,19 +340,52 @@ private static object TranslateSurrogate(object deserializedValue, NewtonSoftJso
                     return GetValue(value);
                 }
 
+                // Bug: #6502 Newtonsoft could not deserialize pure JObject inside an object payload.
+                // If type is `object`, deep-convert object and return as is.
+                if (type == typeof(object))
+                {
+                    return RestoreJToken(j);
+                }
+
                 //The JObject is not of our concern, let Json.NET deserialize it.
                 return j.ToObject(type, parent._serializer);
             }
-            var surrogate = deserializedValue as ISurrogate;
 
             //The deserialized object is a surrogate, unwrap it
-            if (surrogate != null)
+            if (deserializedValue is ISurrogate surrogate)
             {
                 return surrogate.FromSurrogate(parent.system);
             }
             return deserializedValue;
         }
 
+        private static JToken RestoreJToken(JToken value)
+        {
+            switch (value)
+            {
+                case JObject obj:
+                    if (obj["$"] != null)
+                    {
+                        var v = obj["$"].Value<string>();
+                        return new JValue(GetValue(v));
+                    }
+                    var dict = (IDictionary<string, JToken>)obj;
+                    foreach (var kvp in dict)
+                    {
+                        dict[kvp.Key] = RestoreJToken(kvp.Value);
+                    }
+                    return obj;
+                case JArray arr:
+                    for (var i = 0; i < arr.Count; i++)
+                    {
+                        arr[i] = RestoreJToken(arr[i]);
+                    }
+                    return arr;
+                default:
+                    return value;
+            }
+        }
+
         private static object GetValue(string V)
         {
             var t = V.Substring(0, 1);