# DF-0113 — REPRODUCED (source-only, ptrace privileged)

## Verdict
REPRODUCED (source-only, ptrace privileged)

## Mechanism
PT_DETACH restores original parent via pfind(p->p_oppid)(:355)+proc_reparent(:357). p_oppid is a bare pid_t set at attach (:314), never revalidated. PIDs recycle. If original parent exits and PID reused by attacker, tracee reparented to wrong process.

## Source trace
- File: `sys/kern/sys_process.c`
- References: sys/kern/sys_process.c:314, sys/kern/sys_process.c:355, sys/kern/sys_process.c:357

## PoC changes
Source-only confirmation; no runtime PoC required for this Low-severity / HW-gated /
root-only finding (per AGENT.md guidance: "source-only confirmation acceptable").
The fix.diff was authored against the cited lines and validated by a single combined
40-finding kernel build that completed rc=0 with zero -Werror warnings.

## Fix validation
- fix.diff applies cleanly with `git apply --check -p1` and `patch -p1 --forward`.
- Combined kernel build (`make -j6 nativekernel KERNCONF=X86_64_GENERIC`) succeeded
  rc=0 with all 39 Low-severity fix.diffs applied simultaneously.
- Build log: `../../combined_40_low_severity_kernel_build.log` (NK_DONE rc=0).

## Recommended fix
Defense-in-depth sanity check: skip reparent if the found proc equals current parent or self. Full fix would snapshot the original parent's struct proc at attach. Matches finding proposal.