DF-4490

acpi_ec: ec_sci_pend publication race between EcGpeHandler and EcGpeQueryHandler permanently disables the EC GPE (lost AcpiFinishGpe)

Summary

EcGpeHandler queues the query handler via AcpiOsExecute (an async LWKT sendmsg) and returns 0 - transferring the GPE re-enable duty - but publishes ec_sci_pend=TRUE only AFTER the enqueue returns. The helper thread can sample sci_enqueued==FALSE, skip AcpiFinishGpe, and the GPE stays disabled forever: all future EC SCI events (lid, hotkeys, battery/AC/thermal) permanently lost until reboot. Unpriv battery sysctl reads open the window repeatedly. Flag-before-enqueue fix.

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Severity: Low
Status: new
Bucket: Base system — drivers
Confidence: likely
Pass: 2 · GLM 5.3 second pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
CWE: CWE-362
File: sys/dev/acpica/acpi_ec.c
Lines: 693-778
Area: dev
Discovered: 2026-09-20
Updated: 2026-09-20

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: Permanent loss of EC-mediated event delivery (lid suspend, brightness/hotkeys, battery/AC/thermal notifies) plus transient EC I/O degradation to polled mode; availability only
Confidence: likely
Tested: 2026-09-20 19:45:36
Attempts: 0
Runtime: —
Code hash: —
Guest: —
Build cmd: —
Run cmd: —

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: no
Patched reproduced: no
Confidence: likely
Tested: 2026-09-20 19:45:36
Runtime: —
Kernel: per-fix-DF-4490
fix.diff: findings/poc/DF-4490/fix.diff
Runner: df-bsd-reviewer

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PoC verification

Evidence pack

findings/poc/DF-4490 · 1 files

File	Type	Description	Size
verdict.json	file		1.2 KB	view raw

Fix verification

not_testable

baseline no→ patch + rebuild →patched clean

not_testable

set-flag-before-enqueue + rollback-on-failure diff in finding markdown

per-fix-DF-4490

Confirmed kernel references

Detail

Exploit chain

[]

Evidence (decisive lines)

ec_sci_pend published after the async LWKT sendmsg enqueue; consumer can sample FALSE, skip AcpiFinishGpe, and the GPE handler's return 0 leaves the GPE disabled forever (ACPICA contract evgpe.c:1023-1037). Low availability race; QEMU guest DSDT has no PNP0C09 so acpi_ec never attaches there (verified live).

Verdict

not_run: Low availability race, hardware-gated on guest (no EC device)