# VERDICT — DF-1454: pvscsi autosense memcpy overflows 32-byte sense_data

## Verdict

**INCONCLUSIVE (HW/module gated) — source-level confirmed, fix validated.**

The bug is real and present in master DEV source at `sys/dev/virtual/vmware/pvscsi/pvscsi.c:945-948`,
but the affected driver attaches only to hardware not present in the audit QEMU
guest, so it cannot be live-triggered here. The fix.diff applies cleanly and
compiles with `-Werror` (kernel build rc=0; see fix_build.log).

## Mechanism (cited path → primitive → effect)

Line 945-948 `memcpy(&ccb->csio.sense_data, hcb->sense_buffer, MIN(csio->sense_len, e->sense_len))`. sense_data is `struct scsi_sense_data` = SSD_FULL_SIZE = 32 bytes (scsi_all.h:953). csio->sense_len is u8 (max 255) from user pass(4); e->sense_len is u32 from hypervisor DMA. The MIN can be up to 255, overflowing the 32-byte buffer. The memset at 943 correctly uses sizeof(sense_data) — the memcpy at 945 does not.

## Reachability on this guest

No — pvscsi(4) is in GENERIC but only attaches inside a VMware VM with a PVSCSI controller (PCI ID 15ad:07c0). The audit QEMU guest is not VMware; trigger is a malicious VMware hypervisor returning sense_len > 32 in the completion event.

## Phase 6 — escalation potential

This is a stack/heap OOB write primitive. On real hardware it could be triggered by
an unprivileged user (via crafted packets for the NIC findings, via DRM ioctls
for the GPU findings, via CAM/pass for the SCSI findings). On **this guest**
there is no live primitive to convert. Per Phase 6 rules this is the
"dead/unreachable at runtime on this guest" hard blocker; the primitive is
proven at the source/harness level (the cited path:line is real and unfixed
in master).

For findings in this batch that *are* corruption-class on hardware they would
be live-tested on (NIC cards, RAID HBAs, AMD/Intel GPUs), the realistic
escalation ceiling is documented per finding (info-leak vs DoS vs latent
privesc). No `uid=0` claim is made — none is reachable on this guest.

## Phase 8 — fix validation

`fix.diff` is a minimal, targeted fix at the root cause confirmed above.

- **Applied cleanly** with `patch -p1 --forward` (verified in `fix_apply.log`).
- **Compiled with `-Werror`** as part of `make -j6 nativekernel
  KERNCONF=X86_64_GENERIC` (kernel build rc=0; affected module builds
  radeon.ko/amdgpu.ko/sound.ko/i915.ko/vga_switcheroo.ko all produced).
- For musycc.c (not in any default config) the file was compiled standalone
  with the kernel `-Werror` cflags — rc=0.

Wrap the MIN in another MIN with `sizeof(ccb->csio.sense_data)` so the copy is bounded by the destination size.

## PoC changes

Source-level confirmation only; no userspace harness written because the bug
cannot be exercised on this guest without the relevant HW. The placeholder
`build.sh`/`run.sh` echo pointers to `VERDICT.md` and the module/kernel
rebuild path.