DF-1232

Kernel heap address leak to userspace via fibctx->unique in aac_open_aif

Summary

aac_open_aif() at aac.c:3467: fibctx->unique = (*(u_int32_t *)&fibctx & 0xffffffff) = low 32 bits of kmalloc address. copyout to userspace at :3479. On i386: full KVA pointer KASLR bypass. On amd64: low 32 bits pinpoints M_AACBUF slab offset for heap grooming of DF-1231 UAF. Operator group (0640). Fix: use atomic_fetchadd_32 counter seeded with arc4random.

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Severity: Low
Status: new
Bucket: Kernel memory corruption (UAF / OOB write)
Confidence: certain
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U:C:L/I:N/A:N
CWE: CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
File: sys/dev/raid/aac/aac.c
Lines: 3451-3479
Area: dev
Discovered: 2026-07-16
Updated: 2026-07-16

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: leak:4
Confidence: certain
Tested: 2026-07-23 15:26:12
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

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Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: certain
Tested: 2026-07-23 15:26:12
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1232/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-1232 · 2 files

File	Type	Description	Size
VERDICT.md	verdict	verification verdict	869 B	↓ raw
fix.diff	suggested-fix	git-apply-able fix	687 B	view raw

VERDICT.md verdict verification verdict

↓ download raw

DF-1232 - Verification Verdict

Status: reproduced (reproduced=1) Impact: leak:4 Confidence: certain

Finding

Kernel heap address leak to userspace via fibctx->unique in aac_open_aif

Source Location

sys/dev/raid/aac/aac.c:3451-3479

Verdict

Source-confirmed: Kernel heap address leak to userspace via fibctx->unique in aac_open_a. Fix applies and compiles.

Fix Status

fixed: VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

Summary

aac_open_aif() at aac.c:3467: fibctx->unique = ((u_int32_t )&fibctx & 0xffffffff) = low 32 bits of kmalloc address. copyout to userspace at :3479. On i386: full KVA pointer KASLR bypass. On amd64: low 32 bits pinpoints M_AACBUF slab offset for heap grooming of DF-1231 UAF. Operator group (0640). Fix: use atomic_fetchadd_32 counter seeded with arc4random.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: aac_open_aif sets fibctx->unique to low 32 bits of heap address (&fibctx), leaking kernel heap pointer to userspace. Fixed to atomic counter.

Verified recommended fix

Source-confirmed: aac_open_aif sets fibctx->unique to low 32 bits of heap address (&fibctx), leaking kernel heap pointer to userspace. Fixed to atomic counter.

Verdict

Source-confirmed: aac_open_aif sets fibctx->unique to low 32 bits of heap address (&fibctx), leaking kernel heap pointer to userspace. Fixed to atomic counter.