Deallocate resources for DacDbiArrayList with a matching deallocator

Author: hoyosjs

src/coreclr/debug/daccess/dacdbiimpl.cpp

@@ -78,7 +78,7 @@ IDacDbiInterface::IAllocator * g_pAllocator = NULL;
 //            return; // DBI will then free this memory.
 //        }
 //        ...
-//        DeleteDbiMemory(p);
+//        DeleteDbiMemory(p); // DeleteDbiMemory(p, len); if it was an array allocation.
 //     }
 //
 //     Be very careful when using this on classes since Dbi and DAC may be in
@@ -155,6 +155,25 @@ template<class T> void DeleteDbiMemory(T *p)
     g_pAllocator->Free((BYTE*) p);
 }
 
+// Delete memory and invoke dtor for memory allocated with 'operator (forDbi) new[]'
+// There's an inherent risk here - where each element's destructor will get called within
+// the context of the DAC. If the destructor tries to use the CRT allocator logic expecting
+// to hit the DBI's, we could be in trouble. Those objects need to use an export allocator like this.
+template<class T> void DeleteDbiArrayMemory(T *p, int len)
+{
+    if (p == NULL)
+    {
+        return;
+    }
+
+    for (T *cur = p; cur < p + len; cur++)
+    {
+        cur->~T();
+    }
+
+    _ASSERTE(g_pAllocator != NULL);
+    g_pAllocator->Free((BYTE*) p);
+}
 
 //---------------------------------------------------------------------------------------
 // Creates the DacDbiInterface object, used by Dbi.
@@ -818,12 +837,6 @@ SIZE_T DacDbiInterfaceImpl::GetArgCount(MethodDesc * pMD)
     return NumArguments;
 } //GetArgCount
 
-// Allocator to pass to DebugInfoStores, allocating forDBI
-BYTE* InfoStoreForDbiNew(void * pData, size_t cBytes)
-{
-    return new(forDbi) BYTE[cBytes];
-}
-
 // Allocator to pass to the debug-info-stores...
 BYTE* InfoStoreNew(void * pData, size_t cBytes)
 {

src/coreclr/debug/di/rspriv.h

@@ -173,7 +173,7 @@ extern forDbiWorker forDbi;
 // for dbi we just default to new, but we need to have these defined for both dac and dbi
 inline void * operator new(size_t lenBytes, const forDbiWorker &)
 {
-    void * result = new BYTE[lenBytes];
+    void * result = new (nothrow) BYTE[lenBytes];
     if (result == NULL)
     {
         ThrowOutOfMemory();
@@ -183,7 +183,7 @@ inline void * operator new(size_t lenBytes, const forDbiWorker &)
 
 inline void * operator new[](size_t lenBytes, const forDbiWorker &)
 {
-    void * result = new BYTE[lenBytes];
+    void * result = new (nothrow) BYTE[lenBytes];
     if (result == NULL)
     {
         ThrowOutOfMemory();
@@ -198,6 +198,11 @@ void DeleteDbiMemory(T *p)
     delete p;
 }
 
+template<class T> inline
+void DeleteDbiArrayMemory(T *p, int)
+{
+    delete[] p;
+}
 
 
 //---------------------------------------------------------------------------------------

src/coreclr/debug/inc/dacdbiinterface.h

@@ -29,6 +29,7 @@
 //    In the DBI implementation, this can directly call delete (assuming the IAllocator::Free
 //    directly called new).
 template<class T> void DeleteDbiMemory(T *p);
+template<class T> void DeleteDbiArrayMemory(T *p, int len);
 // Need a class to serve as a tag that we can use to overload New/Delete.
 class forDbiWorker {};
 extern forDbiWorker forDbi;

src/coreclr/debug/inc/dacdbistructures.inl

@@ -71,7 +71,7 @@ void DacDbiArrayList<T>::Dealloc()
 
     if (m_pList != NULL)
     {
-        delete [] m_pList;
+        DeleteDbiArrayMemory(m_pList, m_nEntries);
         m_pList = NULL;
     }
     m_nEntries = 0;