CVE-2024-36898

What it actually does

The vulnerability leaves a kfifo uninitialized when software debounce is active on a GPIO line and the line is later reconfigured for edge detection; subsequent edge events are written to and read from this uninitialized buffer, with the read events returned directly to userspace, enabling kernel memory disclosure or corruption.

Why it matters to the business

Local users on affected Linux systems can obtain sensitive kernel data or potentially escalate privileges, increasing the risk of system compromise on servers, embedded devices, and Android-based products that use GPIO edge detection with software debouncing.

How an attack unfolds

An attacker with local access opens a GPIO character device, requests a line with debounce enabled (triggering software debouncing), then reconfigures the line to enable edge detection without allocating the required kfifo; reading the resulting edge events returns data from uninitialized kernel memory, which can be used to leak information or craft further attacks.

How to fix it

Update the Linux kernel to a version containing commit 1a51e24404d77bb3307c1e39eee0d8e86febb1a5 or later; rebuild and deploy the updated kernel on all affected systems; where immediate patching is not possible, restrict unprivileged access to GPIO character devices via device permissions or SELinux/AppArmor policies.

How to confirm the fix worked

Confirm the running kernel contains commit 1a51e24404d77bb3307c1e39eee0d8e86febb1a5 by checking the kernel source or build log; attempt to reproduce the debounce-then-edge-detection sequence in a test environment and verify that events no longer originate from uninitialized memory.

Typical attack path

1. Obtain local shell or user context on the target system
2. Open /dev/gpiochipX and request a line with debounce enabled
3. Reconfigure the same line to enable edge detection
4. Read edge events from the character device to obtain kernel memory contents
5. Use disclosed data to facilitate privilege escalation or further exploitation

How to detect it

Review kernel logs for unexpected GPIO-related warnings or crashes around debounce and edge-event handling; inspect userspace processes that open GPIO character devices and read edge events; correlate any anomalous reads of GPIO event data with process activity.

What your security team should do

• Prioritize kernel updates on all systems exposing GPIO interfaces to unprivileged users
• Audit device permissions for /dev/gpiochip* and restrict access to trusted processes only
• Monitor kernel update channels for backports of the referenced commit into distribution kernels
• Test updated kernels in staging environments before broad deployment