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.
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.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Fri, 28 Aug 2026 07:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | hwmon: (occ) unregister sysfs devices outside occ lock | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-28T06:49:04.992Z
Reserved: 2026-08-26T14:34:25.780Z
Link: CVE-2026-80660
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-28T08:16:51.160
Modified: 2026-08-28T08:16:51.160
Link: CVE-2026-80660
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.