CVE-2022-44556 is a newly discovered vulnerability found in the Direct Rendering Manager (DRM) module, which has been recently allocated a CVE number for identification and reporting purposes. An exploitable lack of proper parameter type validation exists within the DRM module, potentially affecting the availability of affected systems.

This blog post aims to provide exclusive insights, exploit details, code snippets, and relevant references to better understand and mitigate the risk associated with this vulnerability.

Understanding DRM Module

The Direct Rendering Manager (DRM) is a subsystem in the Linux kernel that is responsible for interfacing with Graphics Processing Units (GPUs) in order to provide features such as framebuffer support, 2D acceleration, and 3D rendering. The DRM module is an essential component of Linux-based operating systems that support high-quality graphics and video performance.

Vulnerability Details

This vulnerability is caused by a lack of proper parameter type validation within the DRM subsystem. When certain malicious input or requests are sent to the affected component, it can cause unintended behavior, leading to potential unavailability or crashing of the affected system.

A successful exploit of this vulnerability could result in a Denial of Service (DoS) attack or other system availability issues. This could be particularly relevant and impactful for any systems relying on DRM for critical graphical functionality.

The following code snippet demonstrates the potentially affected area of code in the DRM module

static int drm_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
    /* ... */
    /* Vulnerable section - missing parameter type validation */
    size_t arg_size = _IOC_SIZE(cmd);
    void __user *user_arg = (void __user *)arg;

    /* ... */

Here, the cmd parameter is used to determine the size of user-supplied data. However, the code does not enforce strict type validation or sanity checks on the cmd parameter before using it, leading to the vulnerability.

Exploit Scenario

An attacker who has already gained access to the target system could particularly craft malicious input or requests, leveraging the vulnerability to cause a DoS attack or system crashes. This would significantly affect the availability of affected systems, particularly those relying on DRM for critical graphical functionality.

Mitigation Strategy and Recommendations

It is crucial to address this vulnerability in a timely manner to reduce the risk of successful exploitation. Here are some recommendations for mitigation:

1. Apply any available patches or updates from Linux distribution maintainers that address this specific vulnerability (CVE-2022-44556).
2. Ensure systems are running the latest version of the Linux kernel and all related components, including graphics drivers and firmware.
3. Implement strict access controls and user permissions for all systems and resources to reduce the risk of unauthorized users exploiting the vulnerability.

Original References and Further Reading

For more details on this vulnerability, please refer to the following original references and resources:

1. CVE-2022-44556 - NIST National Vulnerability Database
2. Linux kernel source code
3. Direct Rendering Manager - Wikipedia


CVE-2022-44556 is a significant vulnerability in the DRM module of the Linux kernel. The lack of proper parameter type validation could result in a severe impact on system availability in affected systems. It is essential to remain vigilant of the latest updates and patches to mitigate the risks associated with this vulnerability.


Published on: 11/08/2022 18:15:00 UTC
Last modified on: 03/03/2023 14:52:00 UTC