Fix use-after-free in RecursiveIteratorIterator on reentrant teardown#22478
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iliaal wants to merge 1 commit into
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Fix use-after-free in RecursiveIteratorIterator on reentrant teardown#22478iliaal wants to merge 1 commit into
iliaal 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().
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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.