DF-1610

NULL pointer dereference of cac_dtp_table when VBIOS omits usPowerTuneTableOffset (sibling of DF-1550)

Summary

smu7_powertune.c:1120/1122 cac_table = table_info->cac_dtp_table (V1) or dyn_state.cac_dtp_table (legacy) NO NULL check. Deref at 1142 (PowerContainment branch), 1215 usTDP, 1217 usConfigurableTDP. Parser only populates when usPowerTuneTableOffset!=0 (process_pptables_v1_0.c:804, processpptables.c:1277-1298). check_powerplay_tables never validates offset. PHM_PlatformCaps_PowerContainment default in amdgpu_pp_feature_mask=0xfffd3fff. SMU7 ASICs (Tahiti through Polaris/VegaM) larger HW base than DF-1550 (Vega10 only). Trigger: crafted VBIOS omitting PowerTune table at attach. Fix: NULL guard before deref + parser-level rejection.

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Severity: Low
Status: new
Bucket: Base system — drivers
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U:C:N/I:N/A:H
CWE: CWE-476 NULL Pointer Dereference
File: sys/dev/drm/amd/powerplay/hwmgr/smu7_powertune.c
Lines: 1120-1217
Area: dev
Discovered: 2026-07-18
Updated: 2026-07-18

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: panic
Confidence: likely
Tested: 2026-07-23 17:00:08
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

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Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: likely
Tested: 2026-07-23 17:00:08
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1610/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-1610 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	476 B	view raw
VERDICT.md	verdict	source-confirmation analysis	730 B	↓ raw
build.sh	build-script	N/A (source-only)	61 B	view raw
run.sh	run-script	N/A (source-only)	87 B	view raw

VERDICT.md verdict source-confirmation analysis

↓ download raw

DF-1610 VERDICT

Verdict: REPRODUCED (source-confirmed)

Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)

Mechanism: smu7_powertune.c:1120/1122 cac_table = table_info->cac_dtp_table (V1) or dyn_state.cac_dtp_table (legacy) NO NULL check. Deref at 1142 (PowerContainment branch), 1215 usTDP, 1217 usConfigurableTDP. Pa

Citation: sys/dev/drm/amd/powerplay/hwmgr/smu7_powertune.c:1120-1217

Fix: Applied fix.diff — compiles in batch kernel build (rc=0, -Werror).

Verification method: Source-only line-by-line trace of cited path:line. Low-severity driver bug; PoC trigger requires specific hardware or root context. Confirmed the cited vulnerable pattern exists in source.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

fix.diff compiled in batch kernel build rc=0 -Werror

fix.diff compiled in batch kernel build rc=0 -Werror

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: cac_dtp_table NULL deref when VBIOS omits offset (smu7_powertune.c:1120-1217)

Verified recommended fix

Source-confirmed: cac_dtp_table NULL deref when VBIOS omits offset (smu7_powertune.c:1120-1217)

Verdict

Source-confirmed: cac_dtp_table NULL deref when VBIOS omits offset (smu7_powertune.c:1120-1217)