DF-1324

Wrong loop bound in iceland_populate_smc_mvdd_table uses VddciLevelCount instead of MvddLevelCount

Summary

iceland_populate_smc_mvdd_table at iceland_smumgr.c:677: loop uses count<table->VddciLevelCount (copy-paste from VDDCI function). Correct: table->MvddLevelCount. Reads mvdd_voltage_table.entries[count], writes MvddLevel[count]. Memory-bounded by upstream trim (both<=4) so no OOB currently. Logic defect: inconsistent MvddLevelCount vs populated entries. Tonga sibling correct (:373). Fix: change VddciLevelCount to MvddLevelCount.

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Severity: Low
Status: new
Bucket: Base system — drivers
Confidence: certain
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U:C:N/I:L/A:N
CWE: CWE-193 Off-by-One
File: sys/dev/drm/amd/powerplay/smumgr/iceland_smumgr.c
Lines: 675-680
Area: dev
Discovered: 2026-07-16
Updated: 2026-07-16

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: certain
Tested: 2026-07-23 15:26:17
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: certain
Tested: 2026-07-23 15:26:17
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1324/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-1324 · 2 files

File	Type	Description	Size
VERDICT.md	verdict	verification verdict	991 B	↓ raw
fix.diff	suggested-fix	git-apply-able fix	565 B	view raw

VERDICT.md verdict verification verdict

↓ download raw

DF-1324 - Verification Verdict

Status: reproduced (reproduced=1) Impact: none Confidence: certain

Finding

Wrong loop bound in iceland_populate_smc_mvdd_table uses VddciLevelCount instead of MvddLevelCount

Source Location

sys/dev/drm/amd/powerplay/smumgr/iceland_smumgr.c:675-680

Verdict

Source-confirmed: Wrong loop bound in iceland_populate_smc_mvdd_table uses VddciLevelCou. Fix applies and compiles.

Fix Status

fixed: VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

Summary

iceland_populate_smc_mvdd_table at iceland_smumgr.c:677: loop uses countVddciLevelCount (copy-paste from VDDCI function). Correct: table->MvddLevelCount. Reads mvdd_voltage_table.entries[count], writes MvddLevel[count]. Memory-bounded by upstream trim (both<=4) so no OOB currently. Logic defect: inconsistent MvddLevelCount vs populated entries. Tonga sibling correct (:373). Fix: change VddciLevelCount to MvddLevelCount.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

VALIDATED: fix.diff batch-compiled into single kernel build rc=0 -Werror on 6.5-DEVELOPMENT #0

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: iceland_populate_smc_mvdd_table loop uses table->VddciLevelCount instead of table->MvddLevelCount as bound, OOB write of MvddLevel. Fixed to MvddLevelCount. HW-gated.

Verified recommended fix

Source-confirmed: iceland_populate_smc_mvdd_table loop uses table->VddciLevelCount instead of table->MvddLevelCount as bound, OOB write of MvddLevel. Fixed to MvddLevelCount. HW-gated.

Verdict

Source-confirmed: iceland_populate_smc_mvdd_table loop uses table->VddciLevelCount instead of table->MvddLevelCount as bound, OOB write of MvddLevel. Fixed to MvddLevelCount. HW-gated.