# PoC DF-1576: processpptables unbounded USHORT sub-table offsets

**Class:** OOB read (offset + powerplay_table base, no bounds)
**Cited site:** `sys/dev/drm/amd/powerplay/hwmgr/processpptables.c (many sites)`

## Reproduction status

HW/module gated — **cannot be live-triggered on the audit QEMU guest.**

The audit guest has only virtio + PIIX3 PCI devices (`pciconf -lv` shows no
AMD/Intel GPU, no ath NIC, no AdvanSys SCSI, no mfi/tws/mrsas RAID, etc.),
so the cited code path is not reachable at runtime on this guest.

The bug is **confirmed at the source level** by tracing the cited path:line
in `sys/dev/drm/amd/powerplay/hwmgr/processpptables.c (many sites)` and confirming the vulnerable code is
present in the master DEV kernel tree. The `fix.diff` in this folder is
validated to apply cleanly and compile under `-Werror` (see `VERDICT.md`).

## Mechanism

Every USHORT sub-table offset (usVddcLookupTableOffset/usVddgfxLookupTableOffset/usPPMTableOffset/usMMDependencyTableOffset/usPowerTuneTableOffset/usMclkDependencyTableOffset/usSclkDependencyTableOffset/usHardLimitTableOffset/usPCIETableOffset/usGPIOTableOffset/usStateArrayOffset/usThermalControllerOffset/usFanTableOffset/usVCEStateTableOffset) consumed as powerplay_table+offset NO bounds check vs soft_pp_table_size. PPT_get_num_of_vce_state_entries (1219) NO zero-check on usVCEStateTableOffset.

## Realistic impact ceiling (on suitable HW)

kernel OOB read past the VBIOS table allocation via crafted offsets

## Fix

Add pp_offset_in_bounds(hwmgr, offset, want) helper that checks against hwmgr->soft_pp_table_size; apply it at sub-table consumer entry points.

See `fix.diff` for the git-apply-able patch.

## How to validate the fix

```sh
scp -F dfbsd-qemu/config fix.diff dfbsd:/root/DF-1576.diff
ssh -F dfbsd-qemu/config dfbsd 'cd /usr/src && patch -p1 --forward < /root/DF-1576.diff'
ssh -F dfbsd-qemu/config dfbsd 'cd /usr/src && make -j6 nativekernel KERNCONF=X86_64_GENERIC'
# rc=0 expected; see fix_apply.log + fix_build.log in this folder.
```