DF-0465

Handshake state irrevocably corrupted when noise_begin_session kmalloc(M_NOWAIT) fails

Summary

noise_create_response(:1188-1208) advances r->r_handshake IN PLACE via hs=&r->r_handshake (mix_dh/mix_psk/msg_encrypt) BEFORE noise_begin_session(:1208). noise_begin_session kmalloc(M_NOWAIT|M_ZERO)(:1301) fails under mem pressure -> r->r_handshake already corrupted (ck/hash advanced) but r->r_handshake_state stays HANDSHAKE_RESPONDER. Retry operates on corrupted state -> AEAD tag peer cannot verify -> stuck until REKEY_TIMEOUT=5s re-init. noise_consume_response(:1269-1275) same pattern: commits r->r_handshake=hs(:1272) before noise_begin_session(:1274). Inherited from wireguard-freebsd reference. Transient DoS only.

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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:N/AC:H/PR:N/UI:N/S:U:C:N/I:N/A:L
CWE: CWE-754
File: sys/net/wg/wg_noise.c
Lines: 1188-1275
Area: net
Discovered: 2026-07-01
Updated: 2026-07-01

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: likely
Tested: 2026-07-23 04:51:48
Attempts: 1
Runtime: —
Code hash: 5b113b2284e75a1c
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 04:51:48
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-0465/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-0465 · 2 files

File	Type	Description	Size
VERDICT.md	verdict	source verification verdict	728 B	↓ raw
fix.diff	suggested-fix	fix for logic bug	351 B	view raw

VERDICT.md verdict source verification verdict

↓ download raw

DF-0465 - Verification Verdict

Verdict: REPRODUCED (source-only confirmation)

Bug class: logic

Impact: none

Source file: sys/net/wg/wg_noise.c

Mechanism

CONFIRMED: noise_create_response advances r_handshake in place before noise_begin_session. If kmalloc fails in noise_begin_session, handshake state already corrupted.

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/net/wg/wg_noise.c:1208.

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/net/wg/wg_noise.c:1208. Combined kernel build with all 70 fixes: rc=0, -Werror.

PoC changes

Created fix.diff for DF-0465. No PoC binary (source-only verification).

Verified recommended fix

Document ordering issue (full fix needs state save/restore). Supersedes finding proposal.

Verdict

CONFIRMED source-only: handshake advanced before noise_begin_session. kmalloc fail corrupts state.