DF-1935

CTLFLAG_ANYBODY on writable brightness/mute sysctls allows unprivileged local writes (variant of DF-1892)

Summary

acpi_panasonic_attach L167-173 creates 4 sysctl nodes CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_ANYBODY. kern_sysctl.c:1446-1450 CTLFLAG_ANYBODY skips SYSCAP_NOSYSCTL_WR check. Any unpriv local user writes lcd_brightness and sound_mute (max/min return EPERM on SET). hkey_lcd_brightness L355-361 validates min<=val<=max calls acpi_panasonic_sset AcpiEvaluateObject(SSET). hkey_sound_mute L376-380 sset 0/1. Attacker: any local user Panasonic MAT0019 ACPI ID. Impact: integrity flicker brightness toggle mute continuously; availability starve ACPI serialization; confused deputy kernel HW write no audit. Same pattern as DF-1892 acpi_toshiba. Fix: drop CTLFLAG_ANYBODY.

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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:L
CWE: CWE-732
File: sys/dev/acpica/acpi_panasonic/acpi_panasonic.c
Lines: 167-172
Area: dev
Discovered: 2026-07-20
Updated: 2026-07-20

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: certain
Tested: 2026-07-23 17:00:16
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 17:00:16
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1935/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-1935 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	488 B	view raw
VERDICT.md	verdict	source-confirmation analysis	726 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

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DF-1935 VERDICT

Verdict: REPRODUCED (source-confirmed)

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

Mechanism: acpi_panasonic_attach L167-173 creates 4 sysctl nodes CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_ANYBODY. kern_sysctl.c:1446-1450 CTLFLAG_ANYBODY skips SYSCAP_NOSYSCTL_WR check. Any unpriv local user writes lcd_b

Citation: sys/dev/acpica/acpi_panasonic/acpi_panasonic.c:167-172

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: CTLFLAG_ANYBODY allows unpriv writes to brightness/mute sysctls (acpi_panasonic.c:167-172)

Verified recommended fix

Source-confirmed: CTLFLAG_ANYBODY allows unpriv writes to brightness/mute sysctls (acpi_panasonic.c:167-172)

Verdict

Source-confirmed: CTLFLAG_ANYBODY allows unpriv writes to brightness/mute sysctls (acpi_panasonic.c:167-172)