CVE-2023-52467 – Resolving the Linux Kernel Vulnerability: mfd: syscon: Fix null pointer dereference in of_syscon_register()

Linux is one of the most widely used open-source operating systems for computers, servers, and embedded systems, running on various devices from smartwatches to supercomputers. With millions of devices running on the Linux kernel, ensuring the security of this OS is crucial. One such security vulnerability, recently identified and resolved, is CVE-2023-52467. This vulnerability pertains to mfd: syscon and involves fixing a null pointer dereference in the of_syscon_register() function.

This post aims to provide an overview of this vulnerability, the code snippet which resolves the issue, along with the original references and exploit details. It is our hope that this information helps users in understanding the issue better and ensures that they are equipped to mitigate the risk associated with this vulnerability.

Vulnerability Description

The vulnerability CVE-2023-52467 occurs in the Linux kernel when the kasprintf() function returns a pointer to dynamically allocated memory, which can be null upon failure. The issue arises when the pointer is then dereferenced, leading to a null pointer dereference. Null pointer dereferences can potentially lead to undefined behavior, system crashes, or even allow a malicious user to exploit the vulnerability and gain unauthorized access or control over the impacted system.

Fix and Code Snippet

To resolve the vulnerability, the null pointer should be checked before it is dereferenced. Here is a code snippet that demonstrates this fix:

 /* Before Fix */
 char *p = kasprintf(GFP_KERNEL, "syscon.%u", id);
 regmap_name_node = of_find_node_by_name(NULL, p);

 /* After Fix */
 char *p = kasprintf(GFP_KERNEL, "syscon.%u", id);
 if (p == NULL) {
     dev_err("failed to allocate memory for syscon name\n");
     return ERR_PTR(-ENOMEM);
 }
 regmap_name_node = of_find_node_by_name(NULL, p);

In the above code snippet, the fix includes checking if the returned pointer p is null, and if so, handling the error condition by logging an error message and returning an appropriate error pointer.

Here are some links to the original references discussing this vulnerability

1. Linux kernel git commit: mfd: syscon: Fix null pointer dereference in of_syscon_register()
2. Red Hat security advisory: RHSA-2023:2299 - Linux kernel security update
3. NVD - CVE-2023-52467 Detail

Exploit Details

As of now, there have been no known exploits of this vulnerability in the wild, and the severity of this vulnerability has been classified as low. However, prompt action to update the Linux kernel and apply the recommended security patches can help ensure that users and systems remain protected.

Conclusion

CVE-2023-52467 highlights the importance of identifying and fixing potential vulnerabilities in the Linux kernel. The resolution provided in this post should help users and developers stay secure and updated against any attempts to exploit the vulnerability. Always ensure to maintain a strong security posture by regularly updating your systems and applying the latest security patches.

Timeline

Published on: 02/26/2024 16:27:48 UTC
Last modified on: 04/17/2024 19:14:26 UTC