DF-0347

Undefined behavior: 1<<32 in WPA/RSN cipher selector parsing for unknown OUI

Summary

wpa_cipher(:1198)/rsn_cipher(:1347) return 32 for unknown cipher OUI. Callers: w|=1<<wpa_cipher(:1284), w|=1<<rsn_cipher(:1431). 1<<32 is UB per C99 6.5.7. x86 masks to 5 bits -> 1<<0=CIPHER_WEP. ARM may yield 0. Aggressive compiler could mis-optimize. Remote: assoc req with unknown cipher OUI.

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Severity: Low
Status: new
Bucket: Base system — network stack
Confidence: certain
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U:C:N/I:N/A:N
CWE: CWE-758
File: sys/netproto/802_11/wlan/ieee80211_hostap.c
Lines: 1198-1431
Area: net
Discovered: 2026-06-30
Updated: 2026-06-30

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: certain
Tested: 2026-07-23 04:51:41
Attempts: 1
Runtime: —
Code hash: 29b29fd796206fe7
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: certain
Tested: 2026-07-23 04:51:41
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-0347/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0347 · 2 files

File	Type	Description	Size
VERDICT.md	verdict	source verification verdict	714 B	↓ raw
fix.diff	suggested-fix	fix for ub bug	643 B	view raw

VERDICT.md verdict source verification verdict

↓ download raw

DF-0347 - Verification Verdict

Verdict: REPRODUCED (source-only confirmation)

Bug class: ub

Impact: none

Source file: sys/netproto/802_11/wlan/ieee80211_hostap.c

Mechanism

CONFIRMED: wpa_cipher/rsn_cipher return 32 for unknown cipher OUI. 1<<32 is UB per C99. Fix: return IEEE80211_CIPHER_NONE(6) instead.

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/netproto/802_11/wlan/ieee80211_hostap.c:1198.

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/netproto/802_11/wlan/ieee80211_hostap.c:1198. Combined kernel build with all 70 fixes: rc=0, -Werror.

PoC changes

Created fix.diff for DF-0347. No PoC binary (source-only verification).

Verified recommended fix

Change return 32 to return IEEE80211_CIPHER_NONE in wpa_cipher/rsn_cipher. Matches finding proposal.

Verdict

CONFIRMED source-only: return 32 causes 1<<32 UB. Changed to IEEE80211_CIPHER_NONE.