CVE-2023-52471: Linux Kernel ice_ptp.c Null Pointer Dereference Vulnerability Fixed

In the world of cybersecurity, having updated and accurate information is crucial to protect our systems from attackers. One such vulnerability that was recently resolved in the Linux kernel is CVE-2023-52471, which we will discuss in this article. We will provide you with detailed information about what the vulnerability is, how it works, and how it was fixed, along with code snippets and links to the original references for further understanding.

CVE-2023-52471: Understanding the Vulnerability

CVE-2023-52471 refers to a null pointer dereference vulnerability found in the Linux kernel, specifically in the ice_ptp.c file. This vulnerability could lead to denial of service (DoS) attacks if left unpatched, as it could allow an attacker to crash the kernel, thus bringing down the entire system.

The vulnerability resides in the ice_ptp.c file, which is responsible for handling Precision Time Protocol (PTP) functionality. The issue occurs due to improper error handling when retrieving dynamically allocated memory returned from devm_kasprintf() function.

Issue Details: The 'devm_kasprintf()' Function

The devm_kasprintf() function is responsible for allocating memory dynamically, making it extremely important for developers to handle errors properly. The function has the following signature:

char *devm_kasprintf(struct device *dev, gfp_t gfp, const char *fmt, ...);

A gfp_t flag - specifying how the memory allocation should be performed

3. A formatted string and its arguments - which specifies how the dynamically allocated string should be formatted

The devm_kasprintf() function can return a NULL pointer upon failure, indicating that no memory has been allocated. If this NULL pointer is later dereferenced in the code, it can result in the mentioned null pointer dereference vulnerability, leading to a system crash.

Fixing the Vulnerability: Ice_ptp.c Update

The Linux kernel developers, upon discovering the vulnerability, proposed a fix which involves proper error handling of the pointers returned by the devm_kasprintf() function. By checking if the returned pointer is NULL before using it, developers were able to prevent any null pointer dereference and consequently avoid a crash.

Here's a snippet of the fixed code in ice_ptp.c

char *buf;
buf = devm_kasprintf(dev, GFP_KERNEL, "ptp%u", ptp_idx);
if (!buf)
    return -ENOMEM;

ret = sysfs_create_group(&dev->kobj, &attrs_ice_ptp_attr_group);
if (ret)
    dev_err(dev, "Failed to create sysfs group for ptp%u: %d\n", ptp_idx, ret);

As demonstrated in the code snippet above, the developers now check whether the returned pointer buf is NULL, and if it is, an appropriate error code -ENOMEM is returned, preventing issues caused by null pointer dereference.

For further information and access to the original source codes, please refer to the following links

1. Linux Kernel Git commit - The original Git commit that fixed the vulnerability in the Linux kernel repository.

2. CVE-2023-52471 - The official CVE page providing a brief description and links to further resources.

Conclusion

Vulnerabilities like CVE-2023-52471 highlight the ongoing importance of proper error handling in software development. It's crucial to stay informed about current vulnerabilities in order to protect systems from known exploits. In this case, the Linux kernel developers have successfully identified and fixed the null pointer dereference issue, strengthening the overall security of Linux-based systems.

Timeline

Published on: 02/26/2024 16:27:48 UTC
Last modified on: 04/17/2024 18:59:17 UTC