CVE-2023-52520

What it actually does

A reference leak occurs in the think-lmi driver when kset_find_obj() returns a duplicate attribute without a matching kobject_put(), leaving kernel object references unreleased and enabling memory exhaustion or corruption.

Why it matters to the business

Affected Linux systems on ThinkPad hardware may experience denial of service from gradual resource exhaustion in the platform driver, impacting availability without remote exploit risk.

How an attack unfolds

A local attacker triggers the duplicate attribute path in think-lmi sysfs handling to cause repeated reference leaks that accumulate until kernel memory is exhausted.

How to fix it

Update the Linux kernel to a version containing commit 124cf0ea4b82e1444ec8c7420af4e7db5558c293 or later in the think-lmi driver.

How to confirm the fix worked

Confirm the fix by inspecting the think-lmi.c source for the extracted name validation function and kobject_put() call after kset_find_obj, or verify the running kernel includes the referenced commit.

Typical attack path

1. Obtain local user access on an affected system
2. Interact with think-lmi sysfs attributes to force duplicate kset_find_obj hits
3. Repeat operations to accumulate unreleased references and trigger resource exhaustion

How to detect it

Review kernel logs and dmesg for think-lmi or kobject reference warnings; examine sysfs attribute creation patterns for duplicate handling anomalies.

What your security team should do

• Apply the kernel update containing the reference leak fix on all affected systems
• Audit other platform/x86 drivers for similar kobject handling patterns
• Prioritize patching on systems where local users have access to sysfs attributes