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Fix issue where variance checking uses an unsafe contract by being mo… #21

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Merged
merged 1 commit into from
May 12, 2021
Merged

Fix issue where variance checking uses an unsafe contract by being mo… #21

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24 changes: 19 additions & 5 deletions src/coreclr/vm/methodtable.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9189,7 +9189,7 @@ MethodDesc *MethodTable::GetDefaultConstructor(BOOL forceBoxedEntryPoint /* = FA
//==========================================================================================
// Finds the (non-unboxing) MethodDesc that implements the interface virtual static method pInterfaceMD.
MethodDesc *
MethodTable::ResolveVirtualStaticMethod(MethodTable* pInterfaceType, MethodDesc* pInterfaceMD, BOOL allowNullResult, BOOL checkDuplicates)
MethodTable::ResolveVirtualStaticMethod(MethodTable* pInterfaceType, MethodDesc* pInterfaceMD, BOOL allowNullResult, BOOL checkDuplicates, BOOL allowVariantMatches)
{
if (!pInterfaceMD->IsSharedByGenericMethodInstantiations() && !pInterfaceType->IsSharedByGenericInstantiations())
{
Expand Down Expand Up @@ -9225,7 +9225,7 @@ MethodTable::ResolveVirtualStaticMethod(MethodTable* pInterfaceType, MethodDesc*
return pMD;
}

if (pInterfaceType->HasVariance())
if (pInterfaceType->HasVariance() || pInterfaceType->HasTypeEquivalence())
{
// Variant interface dispatch
MethodTable::InterfaceMapIterator it = IterateInterfaceMap();
Expand All @@ -9240,12 +9240,26 @@ MethodTable::ResolveVirtualStaticMethod(MethodTable* pInterfaceType, MethodDesc*
if (!it.GetInterface()->HasSameTypeDefAs(pInterfaceType))
{
// Variance matches require a typedef match
// Equivalence isn't sufficient, and is uninteresting as equivalent interfaces cannot have static virtuals.
continue;
}

if (it.GetInterface()->CanCastTo(pInterfaceType, NULL))
BOOL equivalentOrVariantCompatible;

if (allowVariantMatches)
{
equivalentOrVariantCompatible = it.GetInterface()->CanCastTo(pInterfaceType, NULL);
}
else
{
// When performing override checking to ensure that a concrete type is valid, require the implementation
// actually implement the exact or equivalent interface.
equivalentOrVariantCompatible = it.GetInterface()->IsEquivalentTo(pInterfaceType, NULL);
}

if (equivalentOrVariantCompatible)
{
// Variant matching interface found
// Variant or equivalent matching interface found
// Attempt to resolve on variance matched interface
pMD = pMT->TryResolveVirtualStaticMethodOnThisType(it.GetInterface(), pInterfaceMD, checkDuplicates);
if (pMD != nullptr)
Expand Down Expand Up @@ -9406,7 +9420,7 @@ MethodTable::VerifyThatAllVirtualStaticMethodsAreImplemented()
MethodDesc *pMD = it.GetMethodDesc();
if (pMD->IsVirtual() &&
pMD->IsStatic() &&
!ResolveVirtualStaticMethod(pInterfaceMT, pMD, /* allowNullResult */ TRUE, /* checkDuplicates */ TRUE))
!ResolveVirtualStaticMethod(pInterfaceMT, pMD, /* allowNullResult */ TRUE, /* checkDuplicates */ TRUE, /* allowVariantMatches */ FALSE))
{
IMDInternalImport* pInternalImport = GetModule()->GetMDImport();
GetModule()->GetAssembly()->ThrowTypeLoadException(pInternalImport, GetCl(), pMD->GetName(), IDS_CLASSLOAD_STATICVIRTUAL_NOTIMPL);
Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/vm/methodtable.h
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Expand Up @@ -2282,7 +2282,7 @@ class MethodTable


// Resolve virtual static interface method pInterfaceMD on this type.
MethodDesc *ResolveVirtualStaticMethod(MethodTable* pInterfaceType, MethodDesc* pInterfaceMD, BOOL allowNullResult, BOOL checkDuplicates = FALSE);
MethodDesc *ResolveVirtualStaticMethod(MethodTable* pInterfaceType, MethodDesc* pInterfaceMD, BOOL allowNullResult, BOOL checkDuplicates = FALSE, BOOL allowVariantMatches = TRUE);

// Try a partial resolve of the constraint call, up to generic code sharing.
//
Expand Down