# DF-0101 — REPRODUCED (source-only)

## Verdict
REPRODUCED (source-only)

## Mechanism
ktrwrite VOP_WRITE entire struct ktr_header sizeof incl caddr_t ktr_buf (ktrace.h:79) which every caller sets to KERNEL addr (&ktp_cache :97 &ktp :155 path :171 etc) but ktrgetheader never touches. Trace file readable by ktrace fd owner leaks kernel heap addresses.

## Source trace
- File: `sys/kern/kern_ktrace.c`
- References: sys/kern/kern_ktrace.c:615, sys/kern/kern_ktrace.c:616, sys/sys/ktrace.h:79

## 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
Emit a sanitized copy of the header with ktr_buf = NULL to the trace file. Matches finding proposal.