The expression that checks a storage pool's target directory nested a
repetition inside another, so a crafted target backtracked
exponentially: "," followed by 22 dashes and "!" took 1.3 s, and every
two more characters four times as long. The field allows 100
characters, so one form post could hold a worker for good (CodeQL
py/redos; the page is for superusers).
The new expression has no nested repetition and accepts exactly the
same targets: compared with the old one on 200,000 random strings over
letters, digits, "/", ".", "-", "_", ",", "!", space and newline, they
agree on every string. A crafted 100-character target is now checked
in microseconds. The tests pin the accepted and refused targets and
time the crafted one.
