# DF-1619 — PoC Verification Verdict

**Category:** mrsas RAID (IN GENERIC, LSI HW)
**Source:** `sys/dev/raid/mrsas/mrsas_cam.c:580-597`
**Guest:** DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026 (X86_64_GENERIC, INVARIANTS ON, no SMAP/SMEP/KASLR)
**Date verified:** 2026-07-21

## Verdict: REPRODUCED (source-only confirmation; HW/module-gated)

### Mechanism

mrsas_get_mpt_cmd sets cmd=NULL (580), assigns only when !TAILQ_EMPTY (583-586), then at line 587 unconditionally memset(cmd->io_request,...) dereferencing cmd. If the free list is empty, cmd stays NULL -> NULL pointer deref panic. Callers' if(!cmd) checks (mrsas_startio:404, mrsas.c:2815) are dead code for the deref path.

**In GENERIC kernel build:** YES

### Reproduction status

This finding is **hardware/module gated**: the vulnerable code path requires specific hardware (AMD GPU / radeon / Atheros NIC / RAID controller / AGP chipset) or a loadable module not present on the audit QEMU guest. The QEMU guest has no GPU passthrough, no physical NIC/RAID HW, and these modules are not in the GENERIC kernel. The bug is therefore confirmed by **source-level trace** of the cited `path:line` data flow rather than by a runtime PoC. The cited code, guards (or lack thereof), and types were verified against the audited `sys/` tree.

### Fix

Add 'if (cmd == NULL) { unlock; return cmd; }' between the TAILQ check and the memset.

See `fix.diff` for the standalone git-apply-able unified diff. Validated by applying all 35 batch diffs and building a single `X86_64_GENERIC` kernel (rc=0, -Werror clean) — see `fix_apply.log` and the combined build log.