Hi,

Four pre-existing bugs found by sashiko-bot during AI-assisted review
of the perf-data-validation hardening series.  All are independent of
that series -- they are latent bugs in surrounding code exposed during
review.

  1. test_bit(sample->cpu, cpu_bitmap) reads out of bounds when
     PERF_SAMPLE_CPU is absent (sample->cpu == (u32)-1) in annotate,
     diff, report, and sched timehist.

  2. Thread reference leak in perf sched latency_switch_event() -- one
     error path does 'return -1' instead of 'goto out_put'.

  3. NULL pointer dereference in perf sched latency_runtime_event() --
     thread_atoms_search() called before the NULL check on the thread
     returned by machine__findnew_thread().

  4. Heap buffer overflow in perf sched map --compact mode --
     comp_cpus allocated based on host CPU count but indexed using a
     MAX_CPUS-sized bitmap, overflowing when analyzing recordings from
     machines with more CPUs than the host.  Also removes the now-dead
     sysconf(_SC_NPROCESSORS_CONF) initialization whose sole consumer
     was the replaced allocation, since max_cpu is dynamically updated
     from the recording's events during processing.

All four require crafted or unusual perf.data inputs to trigger.
Verified with gcc and clang builds, checkpatch, and perf test.

Arnaldo Carvalho de Melo (4):
  perf tools: Guard test_bit from out-of-bounds sample CPU
  perf sched: Fix thread reference leak in latency_switch_event
  perf sched: Fix NULL dereference in latency_runtime_event
  perf sched: Fix comp_cpus heap overflow with cross-machine recordings

 tools/perf/builtin-annotate.c |  3 ++-
 tools/perf/builtin-diff.c     |  3 ++-
 tools/perf/builtin-report.c   |  3 ++-
 tools/perf/builtin-sched.c    | 16 +++++++++-------
 4 files changed, 15 insertions(+), 10 deletions(-)

Developed with AI assistance (Claude/sashiko), tagged in commits.

Thanks a lot,

- Arnaldo