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Fix set___name__ and set___qualname__ deadlock #5956

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Merged
merged 1 commit into from
Jul 12, 2025
Merged

Fix set___name__ and set___qualname__ deadlock #5956

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1 change: 0 additions & 1 deletion Lib/test/test_descr.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4261,7 +4261,6 @@ class C(object):
C.__name__ = 'D.E'
self.assertEqual((C.__module__, C.__name__), (mod, 'D.E'))

@unittest.skip("TODO: RUSTPYTHON, rustpython hang")
def test_evil_type_name(self):
# A badly placed Py_DECREF in type_set_name led to arbitrary code
# execution while the type structure was not in a sane state, and a
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18 changes: 16 additions & 2 deletions vm/src/builtins/type.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -680,7 +680,15 @@ impl PyType {
.heaptype_ext
.as_ref()
.expect("HEAPTYPE should have heaptype_ext");
*heap_type.qualname.write() = str_value;

// Use std::mem::replace to swap the new value in and get the old value out,
// then drop the old value after releasing the lock
let _old_qualname = {
let mut qualname_guard = heap_type.qualname.write();
std::mem::replace(&mut *qualname_guard, str_value)
};
// old_qualname is dropped here, outside the lock scope

Ok(())
}

Expand Down Expand Up @@ -837,7 +845,13 @@ impl PyType {
return Err(vm.new_value_error("type name must not contain null characters"));
}

*self.heaptype_ext.as_ref().unwrap().name.write() = name;
// Use std::mem::replace to swap the new value in and get the old value out,
// then drop the old value after releasing the lock (similar to CPython's Py_SETREF)
let _old_name = {
let mut name_guard = self.heaptype_ext.as_ref().unwrap().name.write();
std::mem::replace(&mut *name_guard, name)
};
// old_name is dropped here, outside the lock scope

Ok(())
}
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