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LibJS: Fix UB downcast during GlobalObject construction

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When constructing a GlobalObject, it has to pass itself as the global
object to its own Shape. Since this is done in the Object constructor,
and Object is a base class of GlobalObject, it's not yet valid to cast
"this" to a GlobalObject*.

Fix this by having Shape store the global object as an Object& and move
Shape::global_object() to GlobalObject.h where we can at least perform a
valid static_cast in the getter.

Found by oss-fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=29267
This commit is contained in:
Andreas Kling 2021-01-05 12:02:59 +01:00
parent 279d2eee04
commit fdd974b7ef
4 changed files with 10 additions and 5 deletions
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2
Libraries/LibJS/Runtime/Object.cpp
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@ -90,7 +90,7 @@ Object* Object::create_empty(GlobalObject& global_object)
Object::Object(GlobalObjectTag)
{
// This is the global object
m_shape = heap().allocate_without_global_object<Shape>(static_cast<GlobalObject&>(*this));
m_shape = heap().allocate_without_global_object<Shape>(*this);
}
Object::Object(ConstructWithoutPrototypeTag, GlobalObject& global_object)