CVE-2022-49598 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
tcp: Fix data-races around sysctl_tcp_mtu_probing.
While reading sysctl_tcp_mtu_probing, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers.
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Analysis
by VulDB Data Team • 07/01/2025
The vulnerability identified as CVE-2022-49598 represents a critical data race condition within the Linux kernel's TCP implementation, specifically affecting the sysctl_tcp_mtu_probing parameter. This issue resides in the kernel's networking subsystem where concurrent access to shared memory locations can lead to unpredictable behavior and potential system instability. The vulnerability manifests when multiple threads or processes attempt to read and modify the MTU probing configuration simultaneously, creating a scenario where the reading process may observe inconsistent or partially updated values. The root cause stems from insufficient synchronization mechanisms during the read operation of the sysctl_tcp_mtu_probing variable, which controls the Maximum Transmission Unit probing behavior in TCP connections. This parameter influences how the kernel handles packet size negotiation and can affect network performance, reliability, and potentially create security implications through inconsistent network behavior.
The technical flaw in this vulnerability directly relates to improper memory access patterns within the kernel's concurrent programming model. When the sysctl_tcp_mtu_probing value is read by network processing threads, there exists a window where the value might be modified by another thread executing a sysctl write operation. This race condition can result in the reader observing corrupted data or inconsistent states, potentially leading to incorrect TCP behavior decisions. The fix implemented addresses this by incorporating READ_ONCE() macro calls in all readers of the sysctl_tcp_mtu_probing variable, ensuring that the read operation is atomic and prevents the compiler and CPU from applying optimizations that could lead to reading stale or corrupted values. This approach aligns with established kernel programming practices for handling concurrent access to shared variables and follows the principles outlined in the Linux kernel's locking documentation and concurrency guidelines.
The operational impact of CVE-2022-49598 extends beyond simple performance degradation to potentially compromise network reliability and system stability. Systems running vulnerable kernel versions may experience intermittent network connectivity issues, unexpected TCP connection failures, or inconsistent packet handling behavior when multiple network operations occur simultaneously. The vulnerability affects any system where TCP MTU probing is actively used, which includes most modern networked systems, servers, and network infrastructure devices. In high-traffic environments or systems with frequent configuration changes, the likelihood of encountering this race condition increases significantly, potentially leading to service disruptions or data corruption in network communications. The vulnerability can be particularly problematic in environments where network configuration is dynamically adjusted, such as in containerized environments, virtualized systems, or network services that frequently modify TCP parameters.
Mitigation strategies for CVE-2022-49598 primarily involve applying the kernel patch that implements the READ_ONCE() protection mechanism. System administrators should prioritize updating their Linux kernel installations to versions containing the fix, typically kernel versions 5.19.13, 6.0.1, or later depending on the specific kernel branch in use. Organizations should conduct thorough testing of kernel updates in staging environments before deployment to ensure compatibility with existing network configurations and applications. Additionally, monitoring systems should be configured to detect unusual network behavior that might indicate race condition occurrences, particularly in high-traffic network environments. The fix addresses the vulnerability at the source level and does not require changes to user-space applications or network configuration files. This remediation aligns with the ATT&CK framework's concept of privilege escalation through kernel vulnerabilities, as the race condition could potentially be exploited to gain elevated privileges or manipulate network traffic. The vulnerability also relates to CWE-362, which describes concurrent execution using shared data structures without proper synchronization, making it a classic example of a race condition in kernel space.