perf sched: Bounds-check prio before test_bit() in timehist

perf sched: Bounds-check prio before test_bit() in timehist

timehist_skip_sample() reads prio from untrusted tracepoint data via
perf_sample__intval(sample, "prev_prio") without bounds validation.
A crafted perf.data with prev_prio >= MAX_PRIO (140) causes test_bit()
to read past the end of the prio_bitmap, which is only MAX_PRIO bits.

Add a prio >= 0 guard before the test_bit() call and skip out-of-range
values (>= MAX_PRIO) that can never match the user's filter set.

The original prio != -1 already let all negatives other than -1 through
(after an undefined-behavior bitmap read); the new prio >= 0 guard
preserves that pass-through behavior — negative means "no priority
info", so the event is shown unfiltered — while fixing the OOB.
Values >= MAX_PRIO are skipped because they cannot be represented in
the filter bitmap.

Fixes: 9b3a48bbe20d9692 ("perf sched timehist: Add --prio option")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Yang Jihong <yangjihong@bytedance.com>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>