{
  "finding_id": "DF-5339",
  "status": "untested",
  "reproduced": false,
  "impact": "none",
  "confidence": "certain",
  "verdict": "Defect is certain at code level and its state machine is proven on the audited guest: mptable_lapic_probe_callback() (mptable.c:818-845) skips DISABLED processor entries BEFORE its duplicate-BSP check, while mptable_lapic_pass2_callback() (mptable.c:674-686) performs the BSP bookkeeping with NO enabled check and KKASSERTs on the second BP-flagged entry regardless of EN. An MP configuration table of [PROC entry #1 flags=EN|BP, PROC entry #2 flags=BP (disabled)] therefore PASSES probe (cpu_count=1, found_bsp=1) and then trips KKASSERT(!arg->found_bsp) at mptable.c:684 during enumerate -> deterministic boot-time kernel panic on INVARIANTS kernels (the stock X86_64_GENERIC enables INVARIANTS, sys/config/X86_64_GENERIC:56). The guest-compiled verbatim-logic reproducer prints exactly this divergence plus both controls (two enabled BSPs correctly rejected by probe; healthy table completes pass2). The end-to-end kernel-boot manifestation is UNTESTED: arming it requires a crafted MP table in firmware-provided EBDA/base/BIOS memory, which stock QEMU/SeaBIOS does not permit injecting and which no unprivileged in-guest actor can influence (same threat class and severity as accepted DF-1034 and DF-5326).",
  "exploit_chain": "",
  "evidence": "run.log \u2014 trigger table: probe PASS then pass2: KERNEL PANIC -> assertion \"!arg->found_bsp\" failed in mptable_lapic_pass2_callback at mptable.c:684; control [EN|BP][EN|BP]: probe EINVAL; control [EN|BP][EN]: pass2 completes. VERDICT.md section 2 walks the two callbacks side by side.",
  "kernel_refs": [
    "sys/platform/pc64/x86_64/mptable.c:683",
    "sys/platform/pc64/x86_64/mptable.c:684",
    "sys/platform/pc64/x86_64/mptable.c:827",
    "sys/platform/pc64/x86_64/mptable.c:837",
    "sys/platform/pc64/x86_64/mptable.c:843",
    "sys/config/X86_64_GENERIC:56"
  ],
  "poc_changes": "No seed PoC existed; authored from scratch. Reproducer copies the cited mptable.c logic verbatim (u_int/u_char semantics preserved); KKASSERT is modeled as a kernel-panic path (setjmp-resumable in the harness), and pmap_mapdev/MMIO access is elided where userland cannot express it (clearly marked in the source header).",
  "attempts": 1,
  "guest_uname": "DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026     root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64",
  "runtime_sec": 300,
  "guest_dirty": 0,
  "build_cmd": "guest: cc -O2 -Wall -Wextra -o /tmp/bsp_asymmetry /tmp/bsp_asymmetry.c",
  "run_cmd": "guest: /tmp/bsp_asymmetry",
  "code_hash": "28a88947d7666aaae00eebcf55fb72a5b7cd847b5a5d9aa60bd24802ef50a881",
  "notes": "Boot-time, malicious-firmware/loader threat class (same bar as accepted DF-1034/DF-5326). Kernel-boot manifestation not armable on the standard QEMU/SeaBIOS guest (no MP-table/SMAP injection, no unprivileged in-guest path) \u2014 verification is the guest-executed verbatim-logic reproducer per the DF-5326 precedent. Guest left clean (only /tmp scratch).",
  "recommended_fix": "pass2: skip disabled PROC entries before BSP bookkeeping, mirroring probe (mptable.c:683)",
  "fix_status": "not_testable",
  "fix_baseline_reproduced": false,
  "fix_patched_reproduced": false,
  "fix_verdict": "fix.diff is authored against the read-only sys/ tree and passes git apply --check, but could not be kernel-build-validated: the bugs kernel manifestation cannot be armed on this guest (needs injected firmware tables), so there is no baseline to compare a patched kernel against.",
  "fix_evidence": "findings/poc/DF-5339/fix.diff (git apply --check passes); reasoning in VERDICT.md"
}