CVE-2022-48742 in Linux
Summary
by MITRE • 06/20/2024
In the Linux kernel, the following vulnerability has been resolved:
rtnetlink: make sure to refresh master_dev/m_ops in __rtnl_newlink()
While looking at one unrelated syzbot bug, I found the replay logic in __rtnl_newlink() to potentially trigger use-after-free.
It is better to clear master_dev and m_ops inside the loop, in case we have to replay it.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/28/2024
The vulnerability identified as CVE-2022-48742 resides within the Linux kernel's routing netlink subsystem, specifically affecting the __rtnl_newlink() function that handles network interface link creation and modification operations. This issue represents a use-after-free vulnerability that can potentially lead to system instability or privilege escalation, as it occurs during the processing of rtnetlink messages that manage network device configuration. The flaw manifests when the kernel attempts to replay network link creation operations, creating a scenario where stale references to master device structures and their associated operation vectors persist in memory after the original objects have been freed.
The technical root cause of this vulnerability stems from improper handling of master device references within the rtnetlink subsystem's link creation logic. When the kernel processes network interface creation requests through the __rtnl_newlink() function, it maintains references to master devices and their corresponding operation vectors through master_dev and m_ops fields. During replay operations, these references are not properly cleared or reset, leading to situations where freed memory locations are still accessed, creating the potential for use-after-free conditions that can be exploited by malicious actors. This behavior violates fundamental memory safety principles and creates opportunities for attackers to manipulate kernel memory structures.
The operational impact of CVE-2022-48742 extends beyond simple system instability, potentially enabling privilege escalation attacks and denial of service conditions within kernel space. When an attacker can trigger the specific sequence that leads to the use-after-free condition, they may be able to corrupt kernel memory, leading to arbitrary code execution with kernel privileges. This vulnerability affects systems running Linux kernels where the rtnetlink subsystem is utilized for network interface management, which encompasses virtually all network-capable Linux systems. The exploitation risk is particularly concerning as it can occur through legitimate network management operations, making it difficult to detect and prevent through traditional network monitoring approaches.
The fix implemented for CVE-2022-48742 addresses the vulnerability by ensuring that master_dev and m_ops fields are properly cleared within the replay loop of the __rtnl_newlink() function. This approach follows established security practices for preventing use-after-free conditions by ensuring that all references to potentially freed memory are reset before the replay logic executes. The solution aligns with common security mitigation strategies such as those recommended in the CWE (Common Weakness Enumeration) catalog for use-after-free vulnerabilities, specifically CWE-416 which addresses the use of freed memory. This fix demonstrates the importance of proper resource management in kernel space and reinforces the principle that all references to freed objects should be explicitly cleared to prevent exploitation.
Organizations should prioritize applying the kernel patches that address this vulnerability as part of their regular security maintenance procedures, particularly in environments where network management operations are frequent or where the systems are exposed to untrusted network traffic. The vulnerability's impact is significant enough that it warrants immediate attention in security-conscious environments, as the potential for privilege escalation means that attackers could gain full control over affected systems. System administrators should also monitor for any unusual network behavior or system instability that might indicate exploitation attempts, as the use-after-free condition could manifest in subtle ways that are difficult to detect through normal system monitoring.