Stack overflow. when serialize object to Json

[liuguiyou]

Describe the bug

When api serialize object to Json, stack overflow

To Reproduce

Steps to reproduce the behavior:

1. Using this version of ASP.NET Core 3.0.0-preview9-19423-09
2. Run this code https://localhost:5001/test/json
3. With these arguments
4. See error

Expected behavior

Not stack overflow

Screenshots

Code solution file

src.zip

[pranavkm]

@ahsonkhan here's a minimal repro without MVC: https://github.com/pranavkm/repro/tree/prkrishn/json-stackoverflow. This stackoverflow seems to be resolved using your patched binary, although I do get a null ref:

Unhandled exception. System.ArgumentNullException: Value cannot be null. (Parameter 'text')
   at System.Text.Json.JsonWriterHelper.NeedsEscaping(ReadOnlySpan`1 value, JavaScriptEncoder encoder)
   at System.Text.Json.Utf8JsonWriter.WriteStringEscape(ReadOnlySpan`1 value)
   at System.Text.Json.Utf8JsonWriter.WriteStringValue(ReadOnlySpan`1 value)
   at System.Text.Json.Utf8JsonWriter.WriteStringValue(String value)
   at System.Text.Json.Serialization.Converters.JsonConverterString.Write(Utf8JsonWriter writer, String value, JsonSerializerOptions options)
   at System.Text.Json.JsonPropertyInfoNotNullable`4.OnWrite(WriteStackFrame& current, Utf8JsonWriter writer)
   at System.Text.Json.JsonPropertyInfo.Write(WriteStack& state, Utf8JsonWriter writer)
   at System.Text.Json.JsonSerializer.HandleObject(JsonPropertyInfo jsonPropertyInfo, JsonSerializerOptions options, Utf8JsonWriter writer, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteObject(JsonSerializerOptions options, Utf8JsonWriter writer, WriteStack& state)
   at System.Text.Json.JsonSerializer.Write(Utf8JsonWriter writer, Int32 originalWriterDepth, Int32 flushThreshold, JsonSerializerOptions options, WriteStack& state)
   at System.Text.Json.JsonSerializer.WriteAsyncCore(Stream utf8Json, Object value, Type inputType, JsonSerializerOptions options, CancellationToken cancellationToken)
   at ConsoleApp17.Program.Main(String[] args) in C:\Users\Pranav\source\repos\ConsoleApp17\ConsoleApp17\Program.cs:line 29
   at ConsoleApp17.Program.<Main>(String[] args)

Could you have a look?

[ahsonkhan]

This issue has been fixed already (in dotnet/corefx#40997) and cannot be reproduced. The root cause was not guarding against null pointers up-front before calling the JavascriptEncoder.

https://github.com/dotnet/corefx/blob/b384d34bcd4674bc0df08a333a4973de8e2ac7ae/src/System.Text.Json/src/System/Text/Json/Writer/JsonWriterHelper.Escaping.cs#L88

although I do get a null ref

Keep in mind, that isn't a null ref, but argument validation - ArgumentNullException.

The patch I shared didn't have that fix at the time, and you'd see that behavior for empty strings in the object you are serializing ("").

[pranavkm]

Thanks for the report @liuguiyou. This issue will be resolved in 3.0 RTM. In the meanwhile, you could consider using Newtonsoft.Json based JSON formatters in your application: https://docs.microsoft.com/en-us/aspnet/core/migration/22-to-30?view=aspnetcore-2.2&tabs=visual-studio#jsonnet-support