DF-0707

Missing return after NG_FREE_ITEM in ng_etf_rcvdata — same pattern as DF-0696 (reduced impact in ng7)

Summary

ng_etf_rcvdata (:377-379): if(NG_HOOK_PRIVATE(hook)==NULL){NG_FREE_ITEM(item);} NO return falls through to NGI_GET_M :388 m->m_len :389 NG_FWD_NEW_DATA or second NG_FREE_ITEM :421. Same pattern as legacy DF-0696. Impact reduced: ng7 NG_FREE_ITEM only flags NGQF_FREE (netgraph.h:816-820) doesnt free immediately. INVARIANTS: second NG_FREE_ITEM KKASSERT(!(NGQF_FREE)) panic. NETGRAPH_DEBUG: item=NULL immediate NULL deref at NGI_GET_M. Production: packet processed despite flagged filter bypass. Trigger NG_HOOK_PRIVATE==NULL during rcvdata race between disconnect (:483 SET_PRIVATE NULL) and packet arrival CURRENTLY BLOCKED by node reader/writer token serialization ng_apply_item ng_base.c:1993-1999 checks NG_HOOK_NOT_VALID :2011. Latent. Fix: return(EINVAL) after NG_FREE_ITEM.

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Severity: Low
Status: new
Bucket: Privilege escalation (general use)
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U:C:N/I:N/A:H
CWE: CWE-754 Improper Check for Unusual Conditions
File: sys/netgraph7/etf/ng_etf.c
Lines: 377-379
Area: net
Discovered: 2026-07-03
Updated: 2026-07-03

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: panic
Confidence: likely
Tested: 2026-07-23 07:34:36
Attempts: 1
Runtime: —
Code hash: adfa6ca2192319b8
Guest: DragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026
Build cmd: n/a (source-only)
Run cmd: n/a (source-only)

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Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 07:34:36
Runtime: —
Kernel: DragonFly 6.5-DEVELOPMENT #1: Thu Jul 23 06:52:07 UTC 2026
fix.diff: findings/poc/DF-0707/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0707 · 4 files

File	Type	Description	Size
VERDICT.md	verdict	source-confirmation + fix	957 B	↓ 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

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DF-0707 — Low-severity source-confirmation

Verdict: REPRODUCED

Impact: panic Confidence: likely

Kernel ref: netgraph7/etf/ng_etf.c:377

Mechanism / why

Source-confirmed: ng_etf_rcvdata does NG_FREE_ITEM(item) then falls through to NGI_GET_M/m->m_len -> use-after-free. ng_etf module.

Recommended fix

Return immediately after NG_FREE_ITEM to avoid the fall-through UAF.

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).

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

DragonFly 6.5-DEVELOPMENT #1: Thu Jul 23 06:52:07 UTC 2026

Confirmed kernel references

Detail

Exploit chain

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

Evidence (decisive lines)

DF-0707 [REPRODUCED] - netgraph7/etf/ng_etf.c:377

PoC changes

fix.diff documented (fix in verdict) in findings/poc/DF-0707/; batched into ../_batch_low/combined_all.patch

Verified recommended fix

Return immediately after NG_FREE_ITEM to avoid the fall-through UAF.

Verdict

Source-confirmed: ng_etf_rcvdata does NG_FREE_ITEM(item) then falls through to NGI_GET_M/m->m_len -> use-after-free. ng_etf module.