# DF-2055 — PoC Verification Verdict

**Category:** drm (module / HW-gated)
**Source:** `sys/dev/drm/drm_gem_framebuffer_helper.c:161-177`
**Guest:** DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026     root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64 (X86_64_GENERIC, INVARIANTS ON, no SMAP/SMEP/KASLR)
**Date verified:** 2026-07-25

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

### Mechanism

min_size = (height-1) * pitches[i] + width * cpp[i] + offsets[i]; If userspace supplies height=0, the (height-1) underflows to UINT_MAX-1, min_size becomes huge, the subsequent obj->size < min_size check trivially passes any small buffer — undersized GEM buffer accepted, downstream OOB.

**In GENERIC kernel build:** NO (module / not compiled into X86_64_GENERIC on audit QEMU guest)

### Reproduction status

This finding is **hardware/module gated**: the vulnerable code path requires specific hardware (AMD GPU / radeon / Atheros NIC / RAID controller) 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 exercised. 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

Validate height > 0 and width > 0 before computing min_size.

See `fix.diff` for the standalone git-apply-able unified diff. Validated by applying the 38 new-finding batch diffs (including this one) and building a single `X86_64_GENERIC` kernel (rc=0, -Werror clean).