Fix use-after-free of object through __isset() and globals #18852
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dstogov
reviewed
Jun 16, 2025
| OBJ_RELEASE(zobj); | ||
| if (UNEXPECTED(obj_is_freed)) { | ||
| retval = &EG(uninitialized_zval); |
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This reverts the return value of __isset() from true to false.
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Effectively, yes. This is later done anyway (see fallthrough path below), at least unless the object is a lazy object. The correct behavior would be to defer the release call until after the zend_lazy_object_must_init() check, which will require some additional branches (only deref when we previously hit the __get branch), which I didn't deem worth it.
If you prefer, I can implement this behavior.
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Fixes GH-18845