# VERDICT — DF-3744

**Status**: inconclusive (source-certain; harness-reproduced arithmetic; kernel path unreachable on this guest)
**reproduced**: 0 (in-kernel) — harness demonstration: YES
**Impact on real hardware**: Medium — CWE-125 Out-of-bounds Read

## Finding
radeon_atombios_get_lvds_info() walks the mode-patch record table with while (*record != ATOM_RECORD_END_TYPE) (:1706) — the only exit conditions are the sentinel byte, known record types stepping by fixed sizes or ucFakeEDIDLength, or an unknown type. Nothing bounds the walk to the VBIOS image: usModePatchTableOffset is an unvalidated u16 (:1697-1705) and record strides are attacker-chosen, so the walk crosses the end of the rdev->bios kmalloc'd image and keeps reading heap. The fake-EDID branch (:1717-1737) kmallocs max(128,len) and memcpy's len (<=255) bytes from record+2 — with the record placed at the image end this copies up to 255 bytes of ADJACENT KERNEL HEAP into bios_hardcoded_edid; if drm_edid_is_valid() passes (checksum 1/256 odds on uncontrolled bytes; guaranteed for the in-image part), those bytes become the connector EDID blob, readable from userspace (DRM_IOCTL_MODE_GETCONNECTOR). Harness on guest: record at image end, len=200 -> 200/200 bytes read beyond image; walk continues 201+ bytes past end until garbage type. Kernel path unreachable on this guest.

## Why not reproduced in-kernel
The QEMU guest is virtio-only (no AMD GPU): `pciconf -l` shows no 1002 device;
`kldstat` shows radeon not loaded. `/boot/kernel/radeon.ko` exists (the vulnerable code ships in
the default install) but cannot attach, so radeon_atombios.c parse paths never execute here.
All conclusions are source-level (path:line above) plus the on-guest harness (harness_lvds.c).

## Harness result
Command: ./run.sh (after ./build.sh)
Expected/observed: fake-EDID len=200: 200/200 bytes read beyond image end; walk continues past end until garbage record type; exit_code=0
Full logs: build.log, run.log.

## Impact / exploit chain
crafted LVDS_Info usModePatchTableOffset + fake-EDID record at image tail -> 200+ B heap OOB read copied into bios_hardcoded_edid -> (checksum luck) EDID blob exposed to userspace; otherwise walk continues OOB -> crash

## Fix
bound the walk to the BIOS image (requires tracking the image length in atom_context) — fix.diff.

## Honest notes
- DF-3744 does NOT re-report pass-1 findings DF-1198/1199/1200 (power-table state_index mismatch,
  asic_ss_info underflow, power-table indices) — different functions/tables/fields.
- fix validation not possible on this guest (no hardware); fix.diff is source-authored only.

## Fix status (batch validation)
Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest `make -j6 nativekernel KERNCONF=X86_64_GENERIC` completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.