CVE-2022-49580 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
ipv4: Fix a data-race around sysctl_fib_multipath_use_neigh.
While reading sysctl_fib_multipath_use_neigh, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader.
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Analysis
by VulDB Data Team • 03/27/2025
The vulnerability CVE-2022-49580 represents a critical data race condition within the Linux kernel's IPv4 networking stack, specifically affecting the fib_multipath_use_neigh sysctl parameter. This issue occurs in the kernel's routing table management subsystem where concurrent access to shared memory locations creates potential for inconsistent data reads and system instability. The vulnerability stems from insufficient synchronization mechanisms when multiple kernel threads attempt to simultaneously read and modify the fib_multipath_use_neigh parameter, which controls how multipath routing entries utilize neighbor information for forwarding decisions.
The technical flaw manifests as a classic race condition where a reader process accessing the sysctl_fib_multipath_use_neigh parameter may observe inconsistent or partially updated values due to concurrent modifications by other kernel threads. This type of vulnerability falls under CWE-362, which specifically addresses race conditions in concurrent programming environments. The issue occurs because the kernel's networking subsystem does not properly employ atomic read operations when accessing this particular sysctl parameter, creating a window where the value being read could be in an intermediate state between updates.
Operationally, this vulnerability could lead to unpredictable routing behavior within the Linux kernel's IPv4 forwarding mechanisms. When the fib_multipath_use_neigh parameter is being modified concurrently while being read, the routing decisions made by the kernel could be based on stale or corrupted data, potentially causing packets to be forwarded incorrectly or dropped entirely. This could result in network connectivity issues, routing table inconsistencies, and in severe cases, complete network service disruption for systems heavily reliant on multipath routing configurations. The impact is particularly concerning in high-performance networking environments where multiple threads may be actively managing routing tables simultaneously.
The resolution for this vulnerability involves implementing proper read synchronization through the use of READ_ONCE() macro, which ensures that readers observe consistent values even when concurrent modifications are occurring. This approach aligns with established kernel development practices and security guidelines for concurrent programming. The fix demonstrates the importance of proper memory ordering and synchronization in kernel space operations, particularly for parameters that control critical network functionality. Organizations should prioritize applying this kernel update to maintain system stability and prevent potential denial of service conditions. The vulnerability highlights the necessity of comprehensive testing for concurrent access patterns in kernel subsystems and reinforces the importance of following established security frameworks such as those recommended by the ATT&CK framework for operating system kernel security.