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DF-2535

OOB read / deterministic panic in mpt_disable_lun via wildcard LUN (loop indexes trt[lun] not trt[i])

Summary

mpt_disable_lun iterates with loop variable i but reads mpt->trt[lun] instead of mpt->trt[i]. When invoked with wildcard LUN (CAM_LUN_WILDCARD=0xFFFFFFFF) together with wildcard target - valid XPT_EN_LUN combination accepted not rejected - code reaches mpt->trt[0xFFFFFFFF].enabled a ~100GB OOB read that faults kernel and panics deterministically. Same typo also breaks LUN-disabling bookkeeping for normal case. Contrast mpt_scsi_tgt_atio at :5038 correctly short-circuits lun>=MPT_MAX_LUNS. mpt_disable_lun has no equivalent guard. Reachable from XPT_EN_LUN enable=0 wildcard target+lun.

Discussion (0)

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PoC verification

Evidence pack

findings/poc/DF-2535 · 6 files
FileTypeDescriptionSize
VERDICT.md verdict Source trace confirming DF-2535 bug is real but HW-gated 1.3 KB ↓ raw
fix.diff suggested-fix Fix typo: change trt[lun] to trt[i] in mpt_disable_lun loop 312 B view raw
env.txt environment Guest gate proof: kldstat, pciconf, camcontrol (no target HBA) 1.1 KB view raw
build.sh build-script No buildable PoC (HW-gated) 384 B view raw
run.sh run-script Gate verification commands 411 B view raw
README.md readme Overview of HW-gated finding 791 B ↓ raw
README.md readme Overview of HW-gated finding
↓ download raw

HW-gated SCSI/FC HBA driver finding

This finding targets a SCSI/FC/SATA HBA driver that is not present in this QEMU/KVM guest (only PIIX3 IDE + virtio). The driver cannot attach and the cited code path is unreachable at runtime.

Reproduction status: NOT REPRODUCED (HW-gated)

  • The source bug is confirmed real by line-by-line source trace (see VERDICT.md).
  • It cannot be triggered because the HBA hardware/driver does not exist on this guest.
  • A defense-in-depth fix.diff has been authored and validated with git apply --check.

Evidence

  • VERDICT.md — full source trace and analysis
  • env.txt — guest environment (kldstat, pciconf, camcontrol gate proof)
  • fix.diff — git-apply-able defense-in-depth fix
  • manifest.json — machine-readable catalog
VERDICT.md verdict Source trace confirming DF-2535 bug is real but HW-gated
↓ download raw

DF-2535 — OOB read / panic in mpt_disable_lun via wildcard LUN

Verdict: NOT REPRODUCED (HW-gated) — source bug CONFIRMED

Hardware gate

No LSI Logic MPT HBA in guest: kldstat shows only kernel/ehci/xhci; pciconf -l shows no LSI device. mpt target-mode LUN enable/disable is never exercised.

Source trace (confirmed real bug)

File: sys/dev/disk/mpt/mpt_cam.c:4335

for (i = 0; i < MPT_MAX_LUNS; i++) {
    if (mpt->trt[lun].enabled) {   // line 4335: TYPO — should be trt[i]
        break;
    }
}

The loop iterates with i but reads mpt->trt[lun] (the function parameter) instead of mpt->trt[i]. When invoked with wildcard LUN (CAM_LUN_WILDCARD=0xFFFFFFFF) together with wildcard target — a valid XPT_EN_LUN combination accepted at line 4322 — lun is 0xFFFFFFFF, so mpt->trt[0xFFFFFFFF].enabled is a ~100GB OOB read that faults the kernel and panics deterministically. The sibling function mpt_scsi_tgt_atio at line 5038 correctly short-circuits lun >= MPT_MAX_LUNS; mpt_disable_lun has no such guard before the buggy loop.

Fix

Changed mpt->trt[lun].enabled to mpt->trt[i].enabled in the loop body. See fix.diff.

Impact (on HW that has the HBA)

Medium — deterministic kernel panic from XPT_EN_LUN with wildcard target+LUN.

Fix verification

not_testable
baseline no→ patch + rebuild →patched clean

not_testable: target driver cannot attach (no target HBA). fix.diff validated with git apply --check (EXIT=0); fix is correct by source trace.

git apply --check findings/poc/DF-2535/fix.diff => EXIT=0. No runtime test possible (no target HBA).
↓ fix.diffDragonFly 6.5-DEVELOPMENT #0 (unpatched with-src baseline — target driver not loadable on this guest)

Confirmed kernel references

Detail

Exploit chain

none — valid hard blocker (driver code path dead at runtime on this guest: no target HBA). No unprivileged->root path.

Evidence (decisive lines)

kldstat -> kernel/ehci/xhci only (no target driver); pciconf -l -> PIIX3 IDE + virtio only (no target HBA); camcontrol devlist -> only <QEMU QEMU DVD-ROM>. Source confirmed at cited lines.

PoC changes

Created findings/poc/DF-2535/{VERDICT.md,fix.diff,manifest.json,env.txt,build.sh,run.sh,README.md}. No PoC source (HW-gated).

Verified recommended fix

Defense-in-depth fix.diff closes the cited path (see findings/poc/DF-2535/fix.diff; git apply --check OK).

Verdict

NOT REPRODUCED (HW-gated). The bug is REAL in source (traced line-by-line): mpt_cam OOB read/panic in mpt_disable_lun (typo trt[lun] vs trt[i] with lun=0xFFFFFFFF wildcard; needs MPT target mode). Gate confirmed: kldstat (only kernel+ehci+xhci; no isp/mpt/sili/trm/sbp module loaded), pciconf -l (no QLogic ISP/LSI MPT/SiliconImage/Tekram/FireWire HBA — only PIIX3 IDE atapci0 + virtio), camcontrol devlist (only QEMU DVD-ROM). The target driver cannot attach so the cited code path is dead at runtime on this guest.