DF-4898

vpo_cam_rescan leaks struct cam_path on every attach and the entire CCB (incl. its callout) when xpt_create_path fails

Summary

The rescan callback frees only the CCB (never the path - xpt_free_ccb does not touch it), leaking cam_path + pinned topology refs on every successful attach; the failure branch leaks the ~1KB CCB + callout. The kernel's own and aac/ciss/mrsas patterns free both. Free-both fix.

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Severity: Info
Status: new
Bucket: Base system — drivers
Confidence: certain
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:N/A:L
CWE: CWE-401
File: sys/dev/disk/vpo/vpo.c
Lines: 176-193
Area: dev
Discovered: 2026-09-24
Updated: 2026-09-24

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: leak
Confidence: certain
Tested: 2026-09-24 20:50:52
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: certain
Tested: 2026-09-24 20:50:52
Runtime: —
Kernel: per-fix-DF-4898
fix.diff: findings/poc/DF-4898/fix.diff
Runner: df-bsd-reviewer

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PoC verification

Evidence pack

findings/poc/DF-4898 · 1 files

File	Type	Description	Size
verdict.json	file		929 B	view raw

Fix verification

not_testable

per-fix-DF-4898

Confirmed kernel references

sys/dev/disk/vpo/vpo.c:176-180
sys/dev/disk/vpo/vpo.c:188-193
sys/cam/cam_xpt.c:4938-4944

Detail

Exploit chain

ZIP/imm device attaches -> rescan runs -> cam_path + topology refs leak per attach

Evidence (decisive lines)

findings/poc/DF-4898/ (this verdict)

Verdict

Hardware-gated (no ZIP on the guest parallel port): the async XPT_SCAN_BUS rescan at attach never releases its resources - the callback frees only the CCB (never xpt_free_path), leaking the kmalloc'd cam_path plus its pinned topology refs on EVERY successful attach; the xpt_create_path failure branch leaks the whole ~1KB CCB incl. its callout. The kernel's own pattern (and aac/ciss/mrsas) frees both. Free-the-path + free-the-ccb-on-fail fix.