mv: symlinks expanded during cross-device move (resource exhaustion / data duplication)
When moving directories across filesystems, uutils mv dereferences symlinks inside the tree, copying their targets as real files/dirs instead of preserving the symlinks. GNU preserves symlinks by default. E.g. a etc_link -> /etc inside the source becomes a full copy of /etc at the destination. Impact: (1) resource exhaustion — a small tree can expand into a huge copy (time/disk DoS); (2) unintended duplication of sensitive paths referenced by symlink; …