DragonFlyBSD Kernel Audit
DF-0019 / fix_run.log
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=== PATCHED KERNEL (#1, with fix.diff applied) ===
kern.version: DragonFly 6.5-DEVELOPMENT #1: Sun Jul 12 15:35:41 UTC 2026

PoC run (/root/poc/DF-0019/df0019 24):
[*] switching pid 870 to bsd4 scheduler...
[+] now running under bsd4 scheduler.
[*] setting kern.usched_bsd4.queue_checks=0...
kern.usched_bsd4.queue_checks: 5
sysctl: kern.usched_bsd4.queue_checks=0: Invalid argument
[*] forking 24 CPU-bound bsd4 kids...
[*] parent survived, reaping kids...
[*] survived — no panic (FIXED kernel or path not hit). exit 0.
DF_EXIT=0

Valid values still accepted:
  sysctl kern.usched_bsd4.queue_checks=5  -> OK (5 -> 5)
  sysctl kern.usched_bsd4.queue_checks=1  -> OK (5 -> 1)
  sysctl kern.usched_bsd4.queue_checks=100 -> OK (1 -> 100)

Rejected values:
  sysctl kern.usched_bsd4.queue_checks=0    -> Invalid argument
  sysctl kern.usched_bsd4.queue_checks=-1   -> Invalid argument
  sysctl kern.usched_bsd4.queue_checks=-999 -> Invalid argument

Result: NO PANIC. Guest stayed up. Fix closes the bug.