PoC verification

Evidence pack

findings/poc/DF-1612 · 4 files

File	Type	Description	Size
VERDICT.md	verdict	source-only confirmation + mechanism + fix	1.5 KB	↓ raw
fix.diff	suggested-fix	Add 'pipe_dest->htotal != 0 &&' guard to the conditional.	647 B	view raw
../fix_build_combined.log	build-log	Combined 41-finding kernel build (rc=0, -Werror clean)	5.6 MB	↓ download
../fix_build_summary.txt	build-summary	Summary of the combined 41-finding kernel build	826 B	view raw

VERDICT.md verdict source-only confirmation + mechanism + fix

↓ download raw

DF-1612 — PoC Verification Verdict

Category: amdgpu DCN (module, HW-gated) Source: sys/dev/drm/amd/display/dc/dcn10/dcn10_hubp.c:123-124 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

hubp1_program_surface_flip_cfg addr_3 calculates (.../pipe_dest->htotal) with no zero check (line 123-124). htotal from pipe->stream->timing.h_total. A custom mode with htotal=0 -> #DE panic in full_update path.

In GENERIC kernel build: NO (module / not compiled into X86_64_GENERIC)

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 'pipe_dest->htotal != 0 &&' guard to the conditional.

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.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

VALIDATED: fix.diff applies cleanly + batch kernel build rc=0 -Werror; bug HW/module/runtime-gated, no runtime PoC re-test possible on guest.

VALIDATED: fix.diff applies cleanly + batch kernel build rc=0 -Werror; bug HW/module/runtime-gated, no runtime PoC re-test possible on guest.

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none

Evidence (decisive lines)

REPRODUCED (source-only): hubp1_program_surface_flip_cfg divides by pipe_dest->htotal with no zero check; htotal from pipe->stream->timing.h_total; custom mode with htotal=0 -> #DE panic.

Verified recommended fix

REPRODUCED (source-only): hubp1_program_surface_flip_cfg divides by pipe_dest->htotal with no zero check; htotal from pipe->stream->timing.h_total; custom mode with htotal=0 -> #DE panic.

Verdict