Fix UAF when setAttributeNS() frees a wrapped attribute child - #237
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Fix UAF when setAttributeNS() frees a wrapped attribute child#237iliaal wants to merge 1 commit into
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dom_set_attribute_ns_modern() handed the element straight to xmlSetNsProp(), which frees the existing attribute's child list, so a live Dom\Text wrapper for one of those children was left pointing at freed memory. Unlink the wrapped children first, as dom_set_attribute_ns_legacy() already does.
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Promoted upstream: php#23348 |
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Dom\Element::setAttributeNS() replaces an existing attribute's value by calling xmlSetNsProp() directly, and libxml2 frees the attribute's child list there. Nothing unlinks the children that still carry a PHP wrapper first, so a live Dom\Text goes on pointing at freed memory: it reports the new attribute text and claims to still be attached. dom_set_attribute_ns_legacy() has always unlinked them, and the modern setAttribute() replaces the value through dom_remove_all_children(), so only the modern namespace-aware setter is missing the step.
No DTD and no entity reference are needed. A single-text-child attribute is enough, which is why the test builds one rather than reusing the phpGH-23331 shape.
Independent of php#23337, which repairs node_list_unlink() itself. Neither fix needs the other, but an attribute holding TEXT/ENTITY_REF/TEXT needs both: with the two applied that case is valgrind-clean, and with either one alone valgrind still reports an invalid read through the surviving wrapper.