{
  "finding_id": "DF-3566",
  "status": "reproduced",
  "reproduced": 1,
  "impact": "dos",
  "confidence": "certain",
  "verdict": "SipHash24_TestVectors calls SipHash_Update(ctx, in, 0) for the empty-message vector, violating SipBufs zero-length contract and panicking any INVARIANTS kernel. Reproduced live on the stock INVARIANTS guest via a kld module built from the unmodified source: panic: SipBuf: invalid parameters with the full backtrace (SipHash24_TestVectors -> SipHash_Update -> SipBuf). The one-line guard (fix.diff) was validated in-kernel: patched module prints result=1 (all 64 vectors pass) and unloads cleanly. Reachability is nil in shipped builds (file is in no build target), so severity is Low; impact ceiling is a developer-configured debug-kernel panic.",
  "exploit_chain": "",
  "evidence": "panic.txt (serial-console panic trace after kldload); kldload_fixed.log (patched module: result=1, no panic, clean unload); run.userland.log (same-source userland build: KASSERT FAILED + SIGABRT at vector 0); VERDICT.md for the source trace",
  "kernel_refs": [
    "sys/crypto/siphash/siphash_test.c:121",
    "sys/crypto/siphash/siphash.c:92",
    "sys/crypto/siphash/siphash.c:95",
    "sys/conf/files:2276",
    "sys/crypto/Makefile:46"
  ],
  "poc_changes": "trigger.c is a new 25-line module shim (DECLARE_MODULE + MOD_LOAD handler calling SipHash24_TestVectors and kprintfing the result); siphash_test.c itself is the unmodified kernel source (md5 3b580668a665816235b2c715bb293734). No changes to the audited source were needed to reproduce.",
  "attempts": 2,
  "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": 420,
  "guest_dirty": 0,
  "build_cmd": "cd /tmp/sipmod && make -f Makefile (SYSDIR=/usr/src/sys, kmod.mk)",
  "run_cmd": "kldload /tmp/sipmod/siphashtest.ko",
  "code_hash": "0c60f163541ce36c4f48b1b65f92a23fd9fa188c9bb8bd4f146609ac5d169844",
  "notes": "Guest reset with vm.sh reset with-src after both the panic run and the fix-validation run; final state clean. The empty-length Update is a functional no-op once the assert is bypassed (SipBuf x=MIN(0,8)=0, no compression), so the vector table is sound and the guard is the complete fix. Also cross-verified in-kernel: patched module result=1 means all 64 reference vectors match.",
  "recommended_fix": "Guard the zero-length update: if (i > 0) SipHash_Update(&ctx, in, i); in siphash_test.c",
  "fix_status": "fixed",
  "fix_baseline_reproduced": 1,
  "fix_patched_reproduced": 0,
  "fix_verdict": "fix.diff applied to siphash_test_fixed.c, module rebuilt and kldloaded on the same stock INVARIANTS guest: no panic, siphashtest: result=1 (no panic) in dmesg, clean kldunload, guest stayed healthy (kldload_fixed.log). Baseline (unpatched) panicked to DDB on the same guest (panic.txt). fix_patched_reproduced=0 because the patched run by definition produces NO panic \u2014 the expected bad behavior is gone.",
  "fix_evidence": "kldload_fixed.log + panic.txt (baseline vs patched on identical guest/kernel)"
}