Fix use-after-free in RecursiveIteratorIterator on reentrant teardown#22478
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Fix use-after-free in RecursiveIteratorIterator on reentrant teardown#22478iliaal wants to merge 1 commit into
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spl_recursive_it_move_forward_ex() tears down the exhausted level after running its sub-iterator, but endChildren() and a sub-iterator's valid() can re-enter through $this->next() and tear that level down first. The no-more-elements branch then dtored a stale iterator pointer, and valid() kept running on a sub-iterator the reentrant call had already freed. Guard the teardown on the level's iterator being unchanged, and hold a reference on the sub-iterator across valid().
devnexen
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Jun 27, 2026
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hasChildren() and getChildren() must not mutate the iteration state: hasChildren() is a predicate and getChildren() returns an iterator for the *current* item. A reentrant rewind()/next() from within either ran spl_recursive_it_rewind_ex()/move_forward_ex(), which tore down the active levels and erealloc()ed object->iterators under the outer move_forward frame, leaving its cached sub-object and iterators[] dangling (use-after-free). Track that we are inside such a call and throw an Error if rewind()/next() re-enters, instead of silently coping with it. The guard is reset across a bailout so a fatal inside the callback cannot leave the iterator wedged. Follow-up to phpGH-22466, phpGH-22478.
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Follow-up to the endChildren()/valid() reentry devnexen raised reviewing #22466. Both new cases reproduce under ASAN. This overlaps #22466 in spl_recursive_it_move_forward_ex(), so whichever lands first, the other takes a trivial rebase.