CVE-2022-27950

What it actually does

A memory leak occurs in the hid-elo HID driver when hid_parse encounters a specific error condition, causing kernel memory to be allocated but never freed.

Why it matters to the business

Systems may gradually exhaust available memory over time when HID devices trigger the error path, leading to degraded performance, instability, or denial of service in environments that rely on affected kernels or virtualized setups.

How an attack unfolds

An attacker with local access supplies a malformed HID report to an Elo device or emulated equivalent, causing the driver to hit the error path in hid_parse and leak kernel memory with each attempt; repeated triggering leads to resource exhaustion.

How to fix it

Upgrade the Linux kernel to 5.16.11 or later (commit 817b8b9c5396d2b2d92311b46719aad5d3339dbe) or apply the corresponding Debian QEMU packages: 1:5.2+dfsg-11+deb11u2 for Debian 11, 1:7.0+dfsg-1 for Debian 12 and 13.

How to confirm the fix worked

Verify the running kernel version is at least 5.16.11, confirm the presence of the fixing commit in the source tree, and test that hid_parse error paths no longer leak memory using kernel memory debugging tools such as kmemleak.

Typical attack path

1. Obtain local user access on a system running an affected kernel or QEMU instance
2. Attach or emulate an Elo HID device that triggers the hid_parse error condition
3. Repeatedly cause the error path to allocate and leak kernel memory
4. Monitor for system-wide memory pressure culminating in denial of service

How to detect it

Review kernel logs for repeated hid_parse failures involving elo devices, correlate with rising slab memory usage for HID allocations, and inspect process or guest activity that interacts with HID subsystems.

What your security team should do

• Prioritize patching production systems that expose HID parsing paths or run QEMU guests with virtual HID devices
• Apply the exact fixed package versions listed for each Debian release and kernel commit
• Monitor memory usage trends on systems that handle HID input as a compensating control until patches are deployed
• Remove or restrict unneeded Elo HID device support where feasible