DF-1186

arcmsr_handle_virtual_command INQUIRY always writes 36 bytes regardless of CAM dxfer_len

Summary

arcmsr_handle_virtual_command INQUIRY at :2958-2973: memcpy(buffer,inqdata,36) unconditional regardless of pccb->csio.dxfer_len. SPC allows allocation_length<36 in CDB[4]. dxfer_len<36 -> up to 35 bytes heap overflow with fixed vendor string. Root/operator via /dev/passN target_id=16. Fix: clamp to min(sizeof(inqdata),dxfer_len).

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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:L/PR:H/UI:N/S:U:C:N/I:L/A:H
CWE: CWE-787 Out-of-bounds Write
File: sys/dev/raid/arcmsr/arcmsr.c
Lines: 2947-3010
Area: dev
Discovered: 2026-07-15
Updated: 2026-07-15

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: panic
Confidence: certain
Tested: 2026-07-25 10:25:05
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: 2026-07-25 10:25:05
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1186/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-1186 · 3 files

File	Type	Description	Size
VERDICT.md	verdict	Source-confirmation verdict for DF-1186	630 B	↓ raw
fix.diff	suggested-fix	Clamp INQUIRY response to min(sizeof(inqdata),dxfer_len)	518 B	view raw
../fix_build.log	build-log	Batch kernel build log (all fixes, rc=0)	5.6 MB	↓ download

VERDICT.md verdict Source-confirmation verdict for DF-1186

↓ download raw

DF-1186 Verification Verdict

Severity: Low Impact class: oob_write Verification method: Source-only confirmation (HW-gated, not triggerable on QEMU guest)

Verdict: REPRODUCED (source-confirmed)

The bug is confirmed in the audited source at the cited path:line. Triggerable but requires specific driver/config.

Fix: Clamp INQUIRY response to min(sizeof(inqdata),dxfer_len)

Fix applied and validated in batch kernel build (rc=0, -Werror).

Fix validation

All 41-fix patches batched into single make -j6 nativekernel KERNCONF=X86_64_GENERIC build. Build result: rc=0, 0 errors (full -Werror clean).

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

VALIDATED: fix.diff applies cleanly + batch kernel build rc=0 -Werror; bug HW/module/runtime-gated, no runtime PoC re-test possible on guest.

VALIDATED: fix.diff applies cleanly + batch kernel build rc=0 -Werror; bug HW/module/runtime-gated, no runtime PoC re-test possible on guest.

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none

Evidence (decisive lines)

REPRODUCED (source-only): arcmsr_handle_virtual_command INQUIRY does memcpy(buffer,inqdata,36) regardless of pccb->csio.dxfer_len; SPC allows allocation_length<36 -> up to 35-byte heap overflow.

Verified recommended fix

REPRODUCED (source-only): arcmsr_handle_virtual_command INQUIRY does memcpy(buffer,inqdata,36) regardless of pccb->csio.dxfer_len; SPC allows allocation_length<36 -> up to 35-byte heap overflow.

Verdict

REPRODUCED (source-only): arcmsr_handle_virtual_command INQUIRY does memcpy(buffer,inqdata,36) regardless of pccb->csio.dxfer_len; SPC allows allocation_length<36 -> up to 35-byte heap overflow.