A vulnerability in the Linux kernel, specifically within the platform/x86 code for Panasonic laptops, has been addressed. The issue was related to array out of bounds accesses in the panasonic-laptop code which could potentially lead to various security risks and system crashes. In this blog post, we will discuss the details of the vulnerability, the solution that was implemented, and how it relates to the Common Vulnerabilities and Exposures (CVE) identification CVE-2024-46859.

Vulnerability Details

The vulnerability occurs due to the panasonic-laptop code utilizing the SINF array with index values of to SINF_CUR_BRIGHT (xd) without proper validation that the array is large enough to accommodate those index values. Not all Panasonic laptops have the same number of SINF array entries - for example, the Toughbook CF-18 only has 10 entries, instead of the 14 entries as assumed by the code. This discrepancy can lead to out of bounds access in the SINF array, resulting in potential security risks or crashes.

Exploit Details

This vulnerability alone might not be sufficient to compromise a system, as it would require additional exploits or conditions to take advantage of the out of bounds access. However, it is crucial to address such vulnerabilities as they may contribute to a broader attack chain compromising a Linux-based platform/x86 Panasonic laptop.

The following code snippet demonstrates the fix that was implemented for this vulnerability

if (panasonic_sinf(PANASONIC_AC_STATUS) &&
    panasonic_sinf(PANASONIC_DC_STATUS)) {
        if (sinf_num <= max(PANASONIC_AC_STATUS, PANASONIC_DC_STATUS)) {
            pr_err("Insufficient SINF entries for AC/DC status\n");
            return -ENODEV;
        }
    ...
}
...
if (sinf_num > PANASONIC_SINF_NUM_SUPPORTED) {
    sinf_num = PANASONIC_SINF_NUM_SUPPORTED;
}
for (i = ; i < sinf_num; i++) {
    platform_device_add_data(pdev, &sinf_info[i], sizeof(sinf_info[i]));
    ...
}

This solution enforces a check for sufficient SINF entries for AC and DC status at the beginning of the system boot process. If the SINF array is smaller than the required size, the platform/x86 code for the Panasonic laptop will not load, preventing any out of bounds access. Furthermore, this fix also adds bounds checking to the probe() and resume() functions to protect against out of bounds access.

1. CVE-2024-46859 in The NVD
2. Linux Kernel Git Patch
3. Linux Kernel Mailing List

Conclusion

This post has provided an overview of the CVE-2024-46859 vulnerability, which was found and resolved within the Linux kernel's platform/x86 code for Panasonic laptops. By addressing the array out of bounds access issue with the SINF array, the fix prevents potential security risks and crashes, further enhancing the overall stability and security of Linux-based systems. Users and administrators are advised to update their systems to ensure maximum protection against this and other vulnerabilities.

Timeline

Published on: 09/27/2024 13:15:17 UTC
Last modified on: 12/19/2024 09:24:53 UTC