From 704f023147b49692cec842427b116e9ee7e64305 Mon Sep 17 00:00:00 2001
From: Tom McDonald <tommcdon@microsoft.com>
Date: Mon, 8 Nov 2021 13:12:57 -0800
Subject: [PATCH] Fix incorrect CCW decoding in GetObjectForCCW (#61193)

* Fix incorrect CCW decoding in GetObjectForCCW

* Fix linux/mac build
---
 src/coreclr/debug/daccess/dacdbiimpl.cpp |  7 ++++
 src/coreclr/debug/daccess/dacimpl.h      |  5 +++
 src/coreclr/debug/daccess/request.cpp    | 46 ++++++++++++++++++------
 3 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/src/coreclr/debug/daccess/dacdbiimpl.cpp b/src/coreclr/debug/daccess/dacdbiimpl.cpp
index c6af447d1b13a..ebb5d12c0ce3a 100644
--- a/src/coreclr/debug/daccess/dacdbiimpl.cpp
+++ b/src/coreclr/debug/daccess/dacdbiimpl.cpp
@@ -4898,6 +4898,10 @@ VMPTR_OBJECTHANDLE DacDbiInterfaceImpl::GetObjectForCCW(CORDB_ADDRESS ccwPtr)
 
     OBJECTHANDLE ohCCW = NULL;
 
+#ifdef FEATURE_COMWRAPPERS
+    if (DACTryGetComWrappersHandleFromCCW(ccwPtr, &ohCCW) != S_OK)
+    {
+#endif
 #ifdef FEATURE_COMINTEROP
     ComCallWrapper *pCCW = DACGetCCWFromAddress(ccwPtr);
     if (pCCW)
@@ -4905,6 +4909,9 @@ VMPTR_OBJECTHANDLE DacDbiInterfaceImpl::GetObjectForCCW(CORDB_ADDRESS ccwPtr)
         ohCCW = pCCW->GetObjectHandle();
     }
 #endif
+#ifdef FEATURE_COMWRAPPERS
+    }
+#endif
 
     VMPTR_OBJECTHANDLE vmObjHandle;
     vmObjHandle.SetDacTargetPtr(ohCCW);
diff --git a/src/coreclr/debug/daccess/dacimpl.h b/src/coreclr/debug/daccess/dacimpl.h
index 84d560e73ec03..948bef16e498d 100644
--- a/src/coreclr/debug/daccess/dacimpl.h
+++ b/src/coreclr/debug/daccess/dacimpl.h
@@ -1498,6 +1498,11 @@ class ClrDataAccess
 
     static LONG s_procInit;
 
+protected:
+#ifdef FEATURE_COMWRAPPERS
+    HRESULT DACTryGetComWrappersHandleFromCCW(CLRDATA_ADDRESS ccwPtr, OBJECTHANDLE* objHandle);
+#endif
+
 public:
     // APIs for picking up the info needed for a debugger to look up an ngen image or IL image
     // from it's search path.
diff --git a/src/coreclr/debug/daccess/request.cpp b/src/coreclr/debug/daccess/request.cpp
index 8d6ae0b3bb85f..4b6f3413b0df1 100644
--- a/src/coreclr/debug/daccess/request.cpp
+++ b/src/coreclr/debug/daccess/request.cpp
@@ -4156,12 +4156,18 @@ TADDR ClrDataAccess::DACGetManagedObjectWrapperFromCCW(CLRDATA_ADDRESS ccwPtr)
     return managedObjectWrapperPtr;
 }
 
-HRESULT ClrDataAccess::DACTryGetComWrappersObjectFromCCW(CLRDATA_ADDRESS ccwPtr, OBJECTREF* objRef)
+HRESULT ClrDataAccess::DACTryGetComWrappersHandleFromCCW(CLRDATA_ADDRESS ccwPtr, OBJECTHANDLE* objHandle)
 {
-    if (ccwPtr == 0 || objRef == NULL)
-        return E_INVALIDARG;
+    HRESULT hr = E_FAIL;
+    TADDR ccw, managedObjectWrapperPtr;
+    ULONG32 bytesRead = 0;
+    OBJECTHANDLE handle;
 
-    SOSDacEnter();
+    if (ccwPtr == 0 || objHandle == NULL)
+    {
+        hr = E_INVALIDARG;
+        goto ErrExit;
+    }
 
     if (!DACIsComWrappersCCW(ccwPtr))
     {
@@ -4169,18 +4175,16 @@ HRESULT ClrDataAccess::DACTryGetComWrappersObjectFromCCW(CLRDATA_ADDRESS ccwPtr,
         goto ErrExit;
     }
 
-    TADDR ccw = CLRDATA_ADDRESS_TO_TADDR(ccwPtr);
+    ccw = CLRDATA_ADDRESS_TO_TADDR(ccwPtr);
 
     // Return ManagedObjectWrapper as an OBJECTHANDLE. (The OBJECTHANDLE is guaranteed to live at offset 0).
-    TADDR managedObjectWrapperPtr = DACGetManagedObjectWrapperFromCCW(ccwPtr);
+    managedObjectWrapperPtr = DACGetManagedObjectWrapperFromCCW(ccwPtr);
     if (managedObjectWrapperPtr == NULL)
     {
         hr = E_FAIL;
         goto ErrExit;
     }
 
-    ULONG32 bytesRead = 0;
-    OBJECTHANDLE handle;
     IfFailGo(m_pTarget->ReadVirtual(managedObjectWrapperPtr, (PBYTE)&handle, sizeof(OBJECTHANDLE), &bytesRead));
     if (bytesRead != sizeof(OBJECTHANDLE))
     {
@@ -4188,9 +4192,31 @@ HRESULT ClrDataAccess::DACTryGetComWrappersObjectFromCCW(CLRDATA_ADDRESS ccwPtr,
         goto ErrExit;
     }
 
-    *objRef = ObjectFromHandle(handle);
+    *objHandle = handle;
 
-    SOSDacLeave();
+    return S_OK;
+
+ErrExit: return hr;
+}
+
+HRESULT ClrDataAccess::DACTryGetComWrappersObjectFromCCW(CLRDATA_ADDRESS ccwPtr, OBJECTREF* objRef)
+{
+    HRESULT hr = E_FAIL;
+
+    if (ccwPtr == 0 || objRef == NULL)
+    {
+        hr = E_INVALIDARG;
+        goto ErrExit;
+    }
+
+    OBJECTHANDLE handle;
+    if (DACTryGetComWrappersHandleFromCCW(ccwPtr, &handle) != S_OK)
+    {
+        hr = E_FAIL;
+        goto ErrExit;
+    }
+
+    *objRef = ObjectFromHandle(handle);
 
     return S_OK;