Look up TEB from OS thread ID instead of DacpThreadData.teb

src/SOS/Strike/strike.cpp

@@ -4408,10 +4408,9 @@ HRESULT PrintThreadsFromThreadStore(BOOL bMiniDump, BOOL bPrintLiveThreadsOnly)
         }
 
         BOOL bSwitchedOutFiber = Thread.osThreadId == SWITCHED_OUT_FIBER_OSID;
+        ULONG id = 0;
         if (!IsKernelDebugger())
         {
-            ULONG id = 0;
-
             if (bSwitchedOutFiber)
             {
                 table.WriteColumn(0, "<<<< ");
@@ -4456,8 +4455,19 @@ HRESULT PrintThreadsFromThreadStore(BOOL bMiniDump, BOOL bPrintLiveThreadsOnly)
         // Apartment state
 #ifndef FEATURE_PAL
         DWORD_PTR OleTlsDataAddr;
-        if (IsWindowsTarget() && !bSwitchedOutFiber
-                && SafeReadMemory(TO_TADDR(Thread.teb + offsetof(TEB, ReservedForOle)),
+        ULONG64 teb = 0;
+        if (IsWindowsTarget() && !bSwitchedOutFiber && id != 0)
+        {
+            ULONG curId;
+            if (SUCCEEDED(g_ExtSystem->GetCurrentThreadId(&curId)) &&
+                SUCCEEDED(g_ExtSystem->SetCurrentThreadId(id)))
+            {
+                g_ExtSystem->GetCurrentThreadTeb(&teb);
+                g_ExtSystem->SetCurrentThreadId(curId);
+            }
+        }
+        if (teb != 0
+                && SafeReadMemory(TO_TADDR(teb + offsetof(TEB, ReservedForOle)),
                             &OleTlsDataAddr,
                             sizeof(OleTlsDataAddr), NULL) && OleTlsDataAddr != 0)
         {

src/tests/SOS.UnitTests/Debuggees/ThreadApartment/ThreadApartment.cs

@@ -0,0 +1,43 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Diagnostics;
+using System.Threading;
+
+internal sealed class ThreadApartment
+{
+    private static readonly ManualResetEventSlim s_staReady = new();
+    private static readonly ManualResetEventSlim s_mtaReady = new();
+
+    private static void Main()
+    {
+        // Create an STA thread using SetApartmentState before Start.
+        // The runtime will call CoInitializeEx(COINIT_APARTMENTTHREADED) when the thread starts.
+        Thread staThread = new Thread(() =>
+        {
+            s_staReady.Set();
+            Thread.Sleep(Timeout.Infinite);
+        });
+        staThread.SetApartmentState(ApartmentState.STA);
+        staThread.IsBackground = true;
+        staThread.Start();
+
+        // Create an MTA thread using SetApartmentState before Start.
+        Thread mtaThread = new Thread(() =>
+        {
+            s_mtaReady.Set();
+            Thread.Sleep(Timeout.Infinite);
+        });
+        mtaThread.SetApartmentState(ApartmentState.MTA);
+        mtaThread.IsBackground = true;
+        mtaThread.Start();
+
+        s_staReady.Wait();
+        s_mtaReady.Wait();
+
+        Debugger.Break();
+
+        throw new Exception("ThreadApartment test complete");
+    }
+}

src/tests/SOS.UnitTests/Debuggees/ThreadApartment/ThreadApartment.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework Condition="'$(BuildProjectFramework)' != ''">$(BuildProjectFramework)</TargetFramework>
+    <TargetFrameworks Condition="'$(BuildProjectFramework)' == ''">$(SupportedSubProcessTargetFrameworks)</TargetFrameworks>
+    <!-- SetApartmentState is Windows-only; this debuggee is only used for Windows tests. -->
+    <NoWarn>$(NoWarn);CA1416</NoWarn>
+  </PropertyGroup>
+</Project>

src/tests/SOS.UnitTests/SOS.cs

@@ -463,6 +463,17 @@ public async Task SimpleThrow(TestConfiguration config)
         await SOSTestHelpers.RunTest(config, debuggeeName: "SimpleThrow", scriptName: "SimpleThrow.script", Output, testTriage: true);
     }
 
+    [SkippableTheory, MemberData(nameof(Configurations))]
+    public async Task ThreadApartment(TestConfiguration config)
+    {
+        if (OS.Kind != OSKind.Windows)
+        {
+            throw new SkipTestException("Apartment state is a Windows COM concept");
+        }
+
+        await SOSTestHelpers.RunTest(config, debuggeeName: "ThreadApartment", scriptName: "ThreadApartment.script", Output);
+    }
+
     [SkippableTheory, MemberData(nameof(Configurations))]
     public async Task AsyncMain(TestConfiguration config)
     {

src/tests/SOS.UnitTests/Scripts/ThreadApartment.script

@@ -0,0 +1,18 @@
+#
+# Tests that clrthreads properly displays COM apartment state (STA/MTA).
+# This test is Windows-only since apartment state is a Windows COM concept.
+#
+
+CONTINUE
+
+LOADSOS
+
+# Verify that clrthreads shows the apartment state column with STA and MTA values.
+# The ThreadApartment debuggee creates one STA and one MTA thread before breaking.
+IFDEF:WINDOWS
+SOSCOMMAND:clrthreads
+VERIFY:\s*ThreadCount:\s+<DECVAL>\s+
+VERIFY:\s+ID\s+OSID\s+ThreadOBJ\s+State.*Apt.*
+VERIFY:.*\bSTA\b.*
+VERIFY:.*\bMTA\b.*
+ENDIF:WINDOWS