A recent vulnerability, CVE-2024-42081, has been identified and resolved in the Linux kernel. This vulnerability involves the drm/xe/xe_devcoredump module. By ensuring proper NULL checks before assignments, the security risk associated with this vulnerability has been mitigated.

This post will provide an overview of the vulnerability, include code snippets illustrating the resolution, and discuss the details of the exploit and its potential implications. Original references and links will be provided for further reading on the subject.

Vulnerability Details

In the Linux kernel's drm/xe/xe_devcoredump module, the vulnerability occurs when 'xe_devcoredump_snapshot *' and 'xe_device *' are assigned without first checking if 'coredump' is NULL. This oversight could lead to potential security risks and system instability.

To address this issue, the developers have revised the code to include a proper NULL check before assignments, and applied additional refinements to enhance the efficiency and maintainability of the codebase.

Code Snippets

Here is a before-and-after comparison of the relevant code segments, illustrating the fix for CVE-2024-42081.

Before (vulnerable)

struct xe_devcoredump_snapshot *snapshot;
struct xe_device *dev;
int ret;

coredump = kzalloc(sizeof(*coredump), GFP_KERNEL);
if (!coredump)
    return -ENOMEM;

dev = coredump->dev = xe->dev;
snapshot = coredump->snapshot = &xe->snapshot;

After (resolved)

struct xe_devcoredump_snapshot *snapshot;
struct xe_device *dev;
int ret;

coredump = kzalloc(sizeof(*coredump), GFP_KERNEL);
if (!coredump)
    return -ENOMEM;

if (coredump) {
    dev = coredump->dev = xe->dev;
    snapshot = coredump->snapshot = &xe->snapshot;
}

As the revised code snippet illustrates, the NULL check for 'coredump' has been implemented, which effectively resolves the vulnerability.

Exploit Details

The absence of a NULL check before assignments in the original code could potentially allow attackers to exploit this vulnerability to compromise system security and stability. By leaving the system susceptible to NULL pointer dereferences, an attacker could cause crashes or gain unauthorized access to memory.

However, the implementation of the NULL check now ensures that 'coredump' is only referenced and assigned when it is non-NULL, preventing potential exploit attempts through this vulnerability.

To learn more about this vulnerability and its resolution, you can refer to the following resources

1. Linux Kernel Mailing List – View the original mailing list discussion, where the vulnerability was reported and the fix was submitted.
2. Linux-git – Review the official git commit, detailing the fix and its various iterations.
3. CVE-2024-42081 – Access the official CVE entry for this vulnerability, covering its description and related resources.

Conclusion

CVE-2024-42081 is an important vulnerability that has now been resolved in the Linux kernel's drm/xe/xe_devcoredump module. By implementing a NULL check before assignment, the associated security risks have been mitigated, and the overall stability of the affected system has been improved. Regular updates and staying informed about the latest vulnerabilities are key factors in maintaining the security and integrity of any system.

Timeline

Published on: 07/29/2024 16:15:07 UTC
Last modified on: 07/30/2024 18:57:21 UTC