Fix by-ref assignment on uninitialized hooked backing value #20943
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Within hooks, the backing value can directly be accessed as if no hooks were present. This was previously handled only in read_property(). zend_fetch_property_address(), which is used for by-ref assignment, will first call get_property_ptr_ptr() and then try read_property(). However, when called on uninitialized backing values, read_property() will return &EG(uninitialized_zval) with an uninitialized property warning. This is problematic for zend_fetch_property_address() because it write to the result of read_property() unless there's an exception. For untyped properties, this can result in writes to &EG(uninitialized_zval) (see oss-fuzz-471486164-001.phpt). For types properties, it will result in an unexpected "Typed property C::$prop must not be accessed before initialization" exception. Fixes OSS-Fuzz #471486164
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Within hooks, the backing value can directly be accessed as if no hooks were present. This was previously handled only in read_property().
zend_fetch_property_address(), which is used for by-ref assignment, will first call get_property_ptr_ptr() and then try read_property(). However, when called on uninitialized backing values, read_property() will return &EG(uninitialized_zval) with an uninitialized property warning. This is problematic for zend_fetch_property_address() because it write to the result of read_property() unless there's an exception.
For untyped properties, this can result in writes to &EG(uninitialized_zval) (see oss-fuzz-471486164-001.phpt). For types properties, it will result in an unexpected "Typed property C::$prop must not be accessed before initialization" exception.
Fixes OSS-Fuzz #471486164