Description

The Assembly.Location property sometimes (5%-50% of the time) returns a corrupted string (most commonly "/", but sometimes other values that appear to be a truncated version of the real path with one extra character appended). This only seems to happen for the System.Net.Sockets.dll assembly and only with COMPlus_PerfMapEnabled=1 and LANG=sv_SE.UTF-8. It did not happen on .NET 6.0, 3.1 or earlier versions with the same code. It does not always happen on .NET 8.

Sometimes the real application also crashes with a segfault around the same point in the code somewhere in libcoreclr.so, but I have not been able to get a proper stack trace or repro the segfault. I cannot be sure if it's part of the same problem, but happy to share a core dump privately.

Reproduction Steps

Extract locationbug.zip, edit go.sh to set DOTNET_ROOT to your .NET 8 SDK directory, make it executable and run it.

The main method code:

	private static void Main(string[] args)
	{
		const string hostname = "www.example.com"; // Host needs to resolve, but does not need to be a MongoDB server

		new MongoClient(new MongoClientSettings	{ Servers = new[] {new MongoServerAddress(hostname)} });
		new HttpClient().GetAsync("http://" + hostname);

		var socketAssembly = typeof(Socket).Assembly;
		Console.Error.WriteLine($"Socket assembly location: {socketAssembly.Location}");

		if (!socketAssembly.Location.EndsWith(".dll", StringComparison.Ordinal))
			throw new ApplicationException($"Unexpected location \"{socketAssembly.Location}\" for assembly FullName={socketAssembly.FullName}");
	}

The Mongo and HttpClient code looks bizarre, but it does not happen without those! (The real application does not use HttpClient, but actually connects to a MongoDB server using MongoClient.)

Expected behavior

Socket assembly location: .../dotnet/sdk-8.0-rc1/shared/Microsoft.NETCore.App/8.0.0-rc.1.23419.4/System.Net.Sockets.dll

This is the output most of the time.

Actual behavior

Sometimes:

Socket assembly location: /
Unhandled exception. System.ApplicationException: Unexpected location "/" for assembly FullName=System.Net.Sockets, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a

Sometimes this happens on the first attempt, sometimes it takes 50 or so.

Regression?

Yes, worked on .NET 6.0, 3.1 and earlier. (Not tested on 7.0.)

Known Workarounds

Don't set COMPlus_PerfMapEnabled=1 or LANG=sv_SE.UTF-8.
It also seems to be very sensitive to the order of statements.

Configuration

.NET SDK 8.0.100-rc.1.23463.5
Linux x64
Reproduced on Linux Mint 20 VM (kernel 5.4.0-163-generic) and multiple Ubuntu 22.04.3 servers (kernels 5.15.0-86-generic and 6.2.0-1013-aws).

Other information

No response