DF-1335

Off-by-one OOB read of vddc_table[MAX_NO_VREG_STEPS=32] in rv770_populate_smc_vddc_table

Summary

rv770_populate_smc_vddc_table at rv770_dpm.c:1135-1142: search loop for(i=0;i<valid_vddc_entries&&max>vddc_table[i].vddc;i++). When max>all entries, i==valid_vddc_entries==32 (max from rv770_construct_vddc_table). vddc_table[32] is 1 past [MAX_NO_VREG_STEPS=32] array. Reads adjacent softc fields. Crafted VBIOS: 32 voltage steps + state requesting vddc above max. Fix: clamp i=valid_vddc_entries-1.

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Severity: Low
Status: new
Bucket: Kernel memory leaks / uninitialized disclosure
Confidence: likely
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U:C:L/I:N/A:N
CWE: CWE-125 Out-of-bounds Read
File: sys/dev/drm/radeon/rv770_dpm.c
Lines: 1124-1274
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: likely
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: likely
Tested: 2026-07-23 15:26:17
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1335/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-1335 · 2 files

File	Type	Description	Size
VERDICT.md	verdict	verification verdict	931 B	↓ raw
fix.diff	suggested-fix	git-apply-able fix	361 B	view raw

VERDICT.md verdict verification verdict

↓ download raw

DF-1335 - Verification Verdict

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

Finding

Off-by-one OOB read of vddc_table[MAX_NO_VREG_STEPS=32] in rv770_populate_smc_vddc_table

Source Location

sys/dev/drm/radeon/rv770_dpm.c:1124-1274

Verdict

Source-confirmed: Off-by-one OOB read of vddc_table[MAX_NO_VREG_STEPS=32] in rv770_popul. 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

rv770_populate_smc_vddc_table at rv770_dpm.c:1135-1142: search loop for(i=0;ivddc_table[i].vddc;i++). When max>all entries, i==valid_vddc_entries==32 (max from rv770_construct_vddc_table). vddc_table[32] is 1 past [MAX_NO_VREG_STEPS=32] array. Reads adjacent softc fields. Crafted VBIOS: 32 voltage steps + state requesting vddc above max. Fix: clamp i=valid_vddc_entries-1.

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: rv770_populate_smc_vddc_table second for loop exits with i==valid_vddc_entries, then accesses vddc_table[i] OOB (off-by-one). Added bounds clamp. HW-gated.

Verified recommended fix

Source-confirmed: rv770_populate_smc_vddc_table second for loop exits with i==valid_vddc_entries, then accesses vddc_table[i] OOB (off-by-one). Added bounds clamp. HW-gated.

Verdict

Source-confirmed: rv770_populate_smc_vddc_table second for loop exits with i==valid_vddc_entries, then accesses vddc_table[i] OOB (off-by-one). Added bounds clamp. HW-gated.