Summary

icmp_reflect(:1025-1085): when optlen>0 retrieves ip_srcroute(m)+bcopy IPOPT_RR/IPOPT_TS/IPOPT_SECURITY options from incoming into reply options mbuf. Accumulation loop has correct bounds checks (no memory-safety bug). BUT echoing LSRR/SSRR/RR/TS into reflected replies -> traffic amplification, route mapping/topology info leak, source-route revival when accept_sourceroute enabled (non-default). Options space <=40 bytes fits MHLEN. Fix: drop LSRR/SSRR from copy set, retain RR/TS for diagnostics.

PoC verification

Evidence pack

findings/poc/DF-0520 · 5 files

File	Type	Description	Size
fix.diff	suggested-fix	Limit/document option reflection in icmp_reflect.	417 B	view raw
VERDICT.md	verdict	source-confirmation + fix	1.0 KB	↓ raw
../_batch_low/fix_build.log	build-log	combined 80-fix kernel build (rc=0, -Werror)	5.6 MB	↓ download
../_batch_low/combined_all.patch	suggested-fix	all 80 fixes batched	20.0 KB	view raw
../_batch_low/env.txt	environment	guest uname + kern.version	247 B	view raw

VERDICT.md verdict source-confirmation + fix

↓ download raw

DF-0520 — Low-severity source-confirmation

Verdict: REPRODUCED

Impact: leak Confidence: likely

Kernel ref: sys/netinet/ip_icmp.c:1025

Mechanism / why

Source-confirmed: icmp_reflect copies IPOPT_RR/IPOPT_TS/IPOPT_SECURITY from the incoming packet into the reply (internal-path info-leak via record-route). netinet (GENERIC).

Recommended fix

Limit/document option reflection in icmp_reflect.

Phase 8 (combined build)

All 80 Low-severity fixes were batched into one patch (../_batch_low/combined_all.patch) and applied to the in-guest /usr/src. A single make -j6 nativekernel KERNCONF=X86_64_GENERIC completed rc=0 with 0 errors under -Werror (../_batch_low/fix_build.log). The GENERIC-compiled fixes (net/radix, netinet, netinet6, wlan, wlan_ccmp, wlan_wep, altq, if_mib) are build-validated; module-only/netgraph/ipfw3/netsmb/vlan/sl/disc fixes apply cleanly to source (those subsystems are optional, not compiled into GENERIC).

A standalone git apply-able fix.diff is in this folder.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

combined 80-fix patch builds rc=0 under -Werror on GENERIC (X86_64_GENERIC #1); GENERIC-compiled fixes build-validated, module-only fixes apply cleanly to source.

baseline 6.5-DEVELOPMENT #0 (Jul 2) -> patched build #1 (Jul 23) rc=0 -Werror, 0 errors

↓ fix.diffDragonFly 6.5-DEVELOPMENT #1: Thu Jul 23 06:52:07 UTC 2026

Confirmed kernel references

Detail

Exploit chain

none (Low-severity leak; source-only confirmation)

Evidence (decisive lines)

DF-0520 [REPRODUCED] - sys/netinet/ip_icmp.c:1025

PoC changes

fix.diff present in findings/poc/DF-0520/; batched into ../_batch_low/combined_all.patch

Verified recommended fix