DF-4824

acpi_dock: _EJ0 executed even when device_detach() of an _EJD-dependent child fails — hardware ejected out from under still-attached drivers

Summary

eject_child ignores device_detach's return and unconditionally runs _EJ0 - a child returning EBUSY (mounted disk, open tty) gets its hardware ejected while still attached (surprise-removal class, driver-dependent fault ceiling). Root-driven undock only. Abort-eject-on-failure 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:H/UI:N/S:U/C:N/I:L/A:L
CWE: CWE-754
File: sys/dev/acpica/acpi_dock/acpi_dock.c
Lines: 300-306
Area: dev
Discovered: 2026-09-24
Updated: 2026-09-24

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: none
Confidence: likely
Tested: 2026-09-24 06:50:22
Attempts: 0
Runtime: —
Code hash: —
Guest: —
Build cmd: —
Run cmd: —

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: —
Patched reproduced: —
Confidence: likely
Tested: 2026-09-24 06:50:22
Runtime: —
Kernel: per-fix-DF-4824
fix.diff: findings/poc/DF-4824/fix.diff
Runner: df-bsd-reviewer

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PoC verification

Evidence pack

findings/poc/DF-4824 · 1 files

File	Type	Description	Size
verdict.json	file		1.0 KB	view raw

Fix verification

not_testable

per-fix-DF-4824

Confirmed kernel references

Detail

Exploit chain

hold open a dock-provided device; sysctl hw.acpi.dock.status=0 -> _EJ0 executes despite EBUSY -> driver runs on vanished hardware

Evidence (decisive lines)

findings/poc/DF-4824/ (this verdict)

Verdict

Logic/robustness gap (no demonstrated memory corruption): acpi_dock_eject_child ignores device_detach's return and unconditionally executes _EJ0 - when a child returns EBUSY (mounted disk, open tty on the docked bus) the firmware ejects hardware out from under still-attached drivers (surprise-removal class, driver-dependent fault ceiling). Root-driven undock only; guest SSDT harness cannot force a child EBUSY deterministically. Abort-eject-on-failure fix (surface error so the state machine does not mark UNDOCKED with dependents attached).