install: finalize ownership before mode, and skip the mode if chown fails - #13629
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…ails set_ownership_and_permissions applied the mode -- including setuid/setgid -- and only then attempted the chown, with no rollback on failure. A failed ownership change therefore left the destination as a setuid file owned by the installing user. install -d had the same ordering. Reproducible unprivileged, no race needed: $ install -m 4755 -o root src dst GNU 9.10 : cannot change ownership of 'dst' -> dst is 600, no setuid uutils : chown failed -> dst is 4755, setuid Swap the order, matching GNU: chown first, and skip the chmod when it fails. This also fixes a second, quieter bug -- chown(2) clears setuid/setgid, so chmod-then-chown silently dropped those bits from successfully installed files. The mode is still applied in full when no ownership change is requested.
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set_ownership_and_permissions applied the mode -- including setuid/setgid -- and only then attempted the chown, with no rollback on failure. A failed ownership change therefore left the destination as a setuid file owned by the installing user. install -d had the same ordering.