[release/7.0] Fix W^X flag for setting ITypeInfo (#75046)

github-actions[bot] · AaronRobinsonMSFT · web-flow · commit 518be5430561 · 2022-09-06T13:32:09.000-07:00
* Fix W^X flag for setting ITypeInfo

* Grab address from the holder.

Co-authored-by: Aaron Robinson &lt;arobins@microsoft.com&gt;
diff --git a/src/coreclr/vm/comcallablewrapper.cpp b/src/coreclr/vm/comcallablewrapper.cpp
@@ -3851,7 +3851,8 @@ void ComMethodTable::SetITypeInfo(ITypeInfo *pNew)
     }
     CONTRACTL_END;
 
-    if (InterlockedCompareExchangeT(&m_pITypeInfo, pNew, NULL) == NULL)
+    ExecutableWriterHolder<ComMethodTable> comMTWriterHolder(this, sizeof(ComMethodTable));
+    if (InterlockedCompareExchangeT(&comMTWriterHolder.GetRW()->m_pITypeInfo, pNew, NULL) == NULL)
     {
         SafeAddRef(pNew);
     }

Original file line number	Diff line number	Diff line change
`@@ -3851,7 +3851,8 @@ void ComMethodTable::SetITypeInfo(ITypeInfo *pNew)`
`3851`	`3851`	`}`
`3852`	`3852`	`CONTRACTL_END;`
`3853`	`3853`
`3854`		`- if (InterlockedCompareExchangeT(&m_pITypeInfo, pNew, NULL) == NULL)`
	`3854`	`+ ExecutableWriterHolder<ComMethodTable> comMTWriterHolder(this, sizeof(ComMethodTable));`
	`3855`	`+ if (InterlockedCompareExchangeT(&comMTWriterHolder.GetRW()->m_pITypeInfo, pNew, NULL) == NULL)`
`3855`	`3856`	`{`
`3856`	`3857`	`SafeAddRef(pNew);`
`3857`	`3858`	`}`