# DF-0080 — REPRODUCED (source-only, root-only)

## Verdict
REPRODUCED (source-only, root-only)

## Mechanism
mem_ioctl MEMRANGE_SET receives flags arg but never checks FWRITE. mmopen enforces securelevel>0||kernel_mem_readonly only for /dev/mem O_RDWR open at :155-158; root at securelevel>=1 opens /dev/mem O_RDONLY (check skipped), issues MEMRANGE_SET to mutate memory range attributes — bypass of the securelevel write gate.

## Source trace
- File: `sys/kern/kern_memio.c`
- References: sys/kern/kern_memio.c:155, sys/kern/kern_memio.c:521, sys/kern/kern_memio.c:559

## 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
In MEMRANGE_SET, return EPERM if (flags & FWRITE) == 0. Matches finding proposal.