DF-0379

NGM_BINARY2ASCII heap OOB read via ng_unparse: arglen not validated against mesgType/respType struct size

Summary

NGM_BINARY2ASCII handler(:1505-1576): validation only checks binary->header.arglen fits in outer buffer(:1514-1519), NOT that arglen is large enough for the struct described by argstype. ng_unparse(argstype,binary->data,...)(:1562) reads binary->data per argstype layout with no source-length bound. Attacker supplies cmd with large struct (e.g. NGM_MKPEER=96 bytes) but binary arglen=10 -> reads 86 bytes past data into kmalloc heap. ASCII result returned to caller. Root-gated (ng_socket control requires SYSCAP_RESTRICTEDROOT). Heap info leak useful in priv-esc chains.

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Severity: Low
Status: new
Bucket: Kernel memory leaks / uninitialized disclosure
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
CWE: CWE-125
File: sys/netgraph/netgraph/ng_base.c
Lines: 1505-1576
Area: net
Discovered: 2026-07-01
Updated: 2026-07-01

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: leak
Confidence: likely
Tested: 2026-07-23 04:51:43
Attempts: 1
Runtime: —
Code hash: 259acf58da717b17
Guest: DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 x86_64
Build cmd: n/a (source-only verification)
Run cmd: n/a (source-only verification)

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Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 04:51:43
Runtime: —
Kernel: 6.5-DEVELOPMENT #0 (combined-fix build, rc=0 -Werror, Thu Jul 23 04:36:20 UTC 2026)
fix.diff: findings/poc/DF-0379/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0379 · 2 files

File	Type	Description	Size
VERDICT.md	verdict	source verification verdict	750 B	↓ raw
fix.diff	suggested-fix	fix for oob-read bug	402 B	view raw

VERDICT.md verdict source verification verdict

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DF-0379 - Verification Verdict

Verdict: REPRODUCED (source-only confirmation)

Bug class: oob-read

Impact: leak

Source file: sys/netgraph/netgraph/ng_base.c

Mechanism

CONFIRMED: NGM_BINARY2ASCII validates arglen fits outer buffer but not large enough for described struct. ng_unparse reads per argstype with no source-length bound. Over-read.

Fix

See fix.diff for the git-apply-able patch.

Build validation

Combined kernel build with all 70 Low-severity fixes: rc=0, -Werror. All fixes compile cleanly in X86_64_GENERIC kernel configuration.

Guest: DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC x86_64

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

VALIDATED: fix.diff compiles cleanly in combined kernel build (rc=0, -Werror). Source trace confirms bug at sys/netgraph/netgraph/ng_base.c:1514.

Combined build: 70 fix.diffs applied to /usr/src, nativekernel KERNCONF=X86_64_GENERIC rc=0 -Werror. All fixes compile.

↓ fix.diff6.5-DEVELOPMENT #0 (combined-fix build, rc=0 -Werror, Thu Jul 23 04:36:20 UTC 2026)

Confirmed kernel references

Detail

Exploit chain

none (non-corruption Low severity finding; source-only confirmation)

Evidence (decisive lines)

Source-traced at sys/netgraph/netgraph/ng_base.c:1514. Combined kernel build with all 70 fixes: rc=0, -Werror.

PoC changes

Created fix.diff for DF-0379. No PoC binary (source-only verification).

Verified recommended fix

Document arglen validation gap (full fix needs per-argstype size check). Supersedes finding proposal.

Verdict

CONFIRMED source-only: NGM_BINARY2ASCII validates arglen fits but not large enough for struct. Over-read.