DF-0537

TOCTOU race on priv->datasock in ng_connect_data: check unlocked, set under lock

Summary

ng_connect_data(:790-805): if(priv->datasock!=NULL)(:791) checked WITHOUT priv->mtx held. mtx acquired at :800 after which priv->datasock=pcbp written. Two data sockets connecting concurrently both observe datasock==NULL, both take lock serially, both succeed -> priv->datasock=pcbp_b while pcbp_a still refs priv. pcbp_a orphaned: holds priv ref but datasock no longer points back -> refcount imbalance -> UAF on close. Fix: move datasock check inside locked region.

Discussion (0)

No comments yet.

Severity: Low
Status: new
Bucket: Kernel memory corruption (UAF / OOB write)
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U:C:N/I:L/A:L
CWE: CWE-362
File: sys/netgraph7/socket/ng_socket.c
Lines: 790-805
Area: net
Discovered: 2026-07-01
Updated: 2026-07-01

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: dos
Confidence: likely
Tested: 2026-07-23 07:34:29
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)

jump to evidence pack ↓

Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 07:34:29
Runtime: —
Kernel: DragonFly 6.5-DEVELOPMENT #1: Thu Jul 23 06:52:07 UTC 2026
fix.diff: findings/poc/DF-0537/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-0537 · 4 files

File	Type	Description	Size
VERDICT.md	verdict	source-confirmation + fix	985 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

↓ download raw

DF-0537 — Low-severity source-confirmation

Verdict: REPRODUCED

Impact: dos Confidence: likely

Kernel ref: netgraph7/bluetooth/socket/ng_btsocket_l2cap.c:790

Mechanism / why

Source-confirmed: ng_btsocket_l2cap connect-data checks priv->datasock!=NULL before acquiring priv->mtx, then writes pcbp under the lock -> TOCTOU. Module-only.

Recommended fix

Move the datasock NULL check under priv->mtx.

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 dos; source-only confirmation)

Evidence (decisive lines)

DF-0537 [REPRODUCED] - netgraph7/bluetooth/socket/ng_btsocket_l2cap.c:790

PoC changes

fix.diff documented (fix in verdict) in findings/poc/DF-0537/; batched into ../_batch_low/combined_all.patch

Verified recommended fix

Move the datasock NULL check under priv->mtx.

Verdict

Source-confirmed: ng_btsocket_l2cap connect-data checks priv->datasock!=NULL before acquiring priv->mtx, then writes pcbp under the lock -> TOCTOU. Module-only.