After migrating from .NET 8 to .NET 9, the application crashes when I send a request to the CoreWCF server from a .NET 9 client application.

[ravipoddar10mca]

After migrating from .NET 8 to .NET 9, the application crashes when I send a request to the CoreWCF server from a .NET 9 client application.

Faulting module name: KERNELBASE.dll, version: 10.0.19041.5198, time stamp: 0xd1eefc71
Exception code: 0xc0000409
Fault offset: 0x0000000000063a9d
Faulting process id: 0xb4c
Faulting application start time: 0x01db40c80b30e79a
Faulting application path: C:\Program Files\Designer.exe
Faulting module path: C:\Windows\System32\KERNELBASE.dll
Report Id: eee996b5-c12b-42b3-a7a6-464371fab361
Faulting package full name:
Faulting package-relative application ID:

[Pyroluk]

My problem might be related. When setting the project to .NET 9, I was also experiencing crashes.

I was able to determine that a stackalloc byte[10240] was causing the issue in conjunction with TcpClient.Read writing into the buffer. Replacing the stackalloc with a normal heap array using new resolved the problem for me.

The code snippet below was consistently crashing at Console.Error.WriteLine. The tcpStream.Read method read about 40–50 bytes into the buffer. This occured within a relatively deep call inside a larger project.

Unfortunately, running this code separately in a new project does not reproduce the issue. As a result, I cannot provide a minimal reproducible example. However, I can offer some insights into what might be happening.

Cheers!

using System.Net.Security;
using System.Net.Sockets;
using System.Text;

using (var tcpClient = new TcpClient { SendTimeout = 30000, ReceiveTimeout = 30000})
{
    #region send HTTP GET
    var uri = new Uri("https://www.microsoft.com/");

    string query = "GET " + uri.PathAndQuery + " HTTP/1.1\r\n" +
                   "Host: " + uri.Host + "\r\n" +
                   "Range: bytes=0-8920" + "\r\n" + 
                   "User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0" +
                   "\r\n\r\n";

    tcpClient.Connect(uri.Host, uri.Port);

    Stream tcpStream;
    if (uri.Port == 80)
        tcpStream = tcpClient.GetStream();
    else
    {
        tcpStream = new SslStream(tcpClient.GetStream());
        ((SslStream)tcpStream).AuthenticateAsClient(uri.Host);
    }

    var queryBytes = Encoding.Default.GetBytes(query);
    tcpStream.Write(queryBytes, 0, queryBytes.Length);
    #endregion

    //#region read content length
    Span<byte> contentSpan = stackalloc byte[10240];

    int bytesRead = tcpStream.Read(contentSpan);
    if (bytesRead == 0)
    {
        Console.Error.WriteLine($"{System.Reflection.MethodBase.GetCurrentMethod()?.Name}: Got no data, not even header, from {uri}");
        return;
    }

    var response = Encoding.Default.GetString(contentSpan);
    Console.WriteLine(response);
    
    ...

    //if (contentLengthSpan == null)
    //{
    //    //Crashes after the WriteLine in case of stackalloc!
    //    Console.Error.WriteLine($"{System.Reflection.MethodBase.GetCurrentMethod().Name}: Could not find Content-Range in header: {url}");
    //    return;
    //}
    //
    //...

}