Fix WXORX issue in EEClass::Destruct (#79696)

janvorli · web-flow · commit d06501087d06 · 2022-12-15T15:06:03.000+01:00
While investigating failures of some coreclr tests when running in an
unloadable context, I've hit AV in EEClass::Destruct in one of the
tests. The reason is that we are missing ExecutableWriterHolder when
updating refCount on pDelegateEEClass-&gt;m_pInstRetBuffCallStub.

This change fixes it.
diff --git a/src/coreclr/vm/class.cpp b/src/coreclr/vm/class.cpp
@@ -162,7 +162,8 @@ void EEClass::Destruct(MethodTable * pOwningMT)
         }
         if (pDelegateEEClass->m_pInstRetBuffCallStub)
         {
-            pDelegateEEClass->m_pInstRetBuffCallStub->DecRef();
+            ExecutableWriterHolder<Stub> stubWriterHolder(pDelegateEEClass->m_pInstRetBuffCallStub, sizeof(Stub));
+            stubWriterHolder.GetRW()->DecRef();
         }
         // While m_pMultiCastInvokeStub is also a member,
         // it is owned by the m_pMulticastStubCache, not by the class

Original file line number	Diff line number	Diff line change
`@@ -162,7 +162,8 @@ void EEClass::Destruct(MethodTable * pOwningMT)`
`162`	`162`	`}`
`163`	`163`	`if (pDelegateEEClass->m_pInstRetBuffCallStub)`
`164`	`164`	`{`
`165`		`- pDelegateEEClass->m_pInstRetBuffCallStub->DecRef();`
	`165`	`+ ExecutableWriterHolder<Stub> stubWriterHolder(pDelegateEEClass->m_pInstRetBuffCallStub, sizeof(Stub));`
	`166`	`+ stubWriterHolder.GetRW()->DecRef();`
`166`	`167`	`}`
`167`	`168`	`// While m_pMultiCastInvokeStub is also a member,`
`168`	`169`	`// it is owned by the m_pMulticastStubCache, not by the class`