DF-1621

Unbounded bcopy of user-controlled csio->cdb_len into 32-byte CDB32 frame (DF-1356/1547 class)

Summary

mrsas_cam.c:489-492 bcopy(cdb_ptr/cdb_bytes, CDB32, csio->cdb_len). CDB32 is u8[32] (mrsas.h:301) at offset 0x40 in 256-byte io_request frame. csio->cdb_len is u8 max 255. cdb_len>32 overwrites RaidContext(0x60)+SGL(0x80) -> DMA to attacker-influenced addresses. Today in-tree periphs cap at IOCDBLEN=16 (scsi_sg.c:507). Defense-in-depth missing: sibling mpr_sas.c:2105 has KASSERT, amr DF-1356. Fix: reject cdb_len > sizeof(CDB32).

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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:H/PR:L/UI:N/S:U:C:N/I:N/A:N
CWE: CWE-787 Out-of-bounds Write
File: sys/dev/raid/mrsas/mrsas_cam.c
Lines: 489-492
Area: dev
Discovered: 2026-07-18
Updated: 2026-07-18

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: panic
Confidence: likely
Tested: 2026-07-23 17:00:08
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: likely
Tested: 2026-07-23 17:00:08
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1621/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-1621 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	691 B	view raw
VERDICT.md	verdict	source-confirmation analysis	710 B	↓ raw
build.sh	build-script	N/A (source-only)	61 B	view raw
run.sh	run-script	N/A (source-only)	87 B	view raw

VERDICT.md verdict source-confirmation analysis

↓ download raw

DF-1621 VERDICT

Verdict: REPRODUCED (source-confirmed)

Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)

Mechanism: mrsas_cam.c:489-492 bcopy(cdb_ptr/cdb_bytes, CDB32, csio->cdb_len). CDB32 is u8[32] (mrsas.h:301) at offset 0x40 in 256-byte io_request frame. csio->cdb_len is u8 max 255. cdb_len>32 overwrites RaidCo

Citation: sys/dev/raid/mrsas/mrsas_cam.c:489-492

Fix: Applied fix.diff — compiles in batch kernel build (rc=0, -Werror).

Verification method: Source-only line-by-line trace of cited path:line. Low-severity driver bug; PoC trigger requires specific hardware or root context. Confirmed the cited vulnerable pattern exists in source.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

fix.diff compiled in batch kernel build rc=0 -Werror

fix.diff compiled in batch kernel build rc=0 -Werror

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: unclamped csio->cdb_len bcopy into CDB32[32] (mrsas_cam.c:489-492)

Verified recommended fix

Source-confirmed: unclamped csio->cdb_len bcopy into CDB32[32] (mrsas_cam.c:489-492)

Verdict

Source-confirmed: unclamped csio->cdb_len bcopy into CDB32[32] (mrsas_cam.c:489-492)