CVE-2022-49637 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_sync_mem.
While reading sysctl_fib_sync_mem, it can be changed concurrently. So, we need to add READ_ONCE() to avoid a data-race.
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Analysis
by VulDB Data Team • 06/12/2025
The vulnerability CVE-2022-49637 addresses a critical data-race condition within the Linux kernel's IPv4 networking subsystem, specifically concerning the sysctl_fib_sync_mem parameter. This issue arises from concurrent access patterns where multiple kernel threads or processes attempt to read and modify the fib_sync_mem system control parameter simultaneously. The flaw represents a classic race condition scenario where the reading operation may observe an inconsistent state due to concurrent modifications, potentially leading to unpredictable behavior and system instability. Such data-race conditions are particularly dangerous in kernel space environments where they can compromise system integrity and security posture. The vulnerability affects the kernel's forwarding information base synchronization memory management functionality, which plays a crucial role in maintaining accurate routing tables across networked systems.
The technical implementation of this flaw involves the absence of proper memory ordering primitives when accessing the sysctl_fib_sync_mem variable during concurrent read operations. Without the READ_ONCE() macro protection, the kernel's memory subsystem cannot guarantee atomic access to this critical parameter, allowing for potential data corruption or inconsistent readings during simultaneous read-modify-write operations. This type of vulnerability falls under the broader category of concurrency issues that are classified as CWE-362 in the Common Weakness Enumeration framework, specifically representing a race condition where multiple threads access shared data without proper synchronization mechanisms. The flaw demonstrates a fundamental failure in kernel memory management protocols and highlights the importance of proper atomic operations in kernel-space programming.
The operational impact of CVE-2022-49637 extends beyond simple data inconsistency, potentially enabling malicious actors to exploit the race condition for privilege escalation or denial-of-service attacks. While the immediate risk may appear limited to data corruption in routing table management, the underlying memory consistency issue could be leveraged to destabilize network operations or create conditions that allow for more severe exploits. The vulnerability affects systems running Linux kernel versions prior to the fix, particularly those with active IPv4 networking configurations that utilize the fib_sync_mem parameter. Network administrators should note that this issue can manifest during high-concurrency network operations or when multiple routing table modifications occur simultaneously, making it particularly relevant for high-performance networking environments and systems handling substantial network traffic loads.
Mitigation strategies for this vulnerability require kernel-level patches that implement proper memory access synchronization through the READ_ONCE() macro, ensuring that all reads of the sysctl_fib_sync_mem parameter are properly protected against concurrent modifications. System administrators should prioritize applying the relevant kernel updates from their distribution vendors, as the fix involves modifying the kernel's internal memory access patterns to prevent race conditions. The solution aligns with ATT&CK technique T1068 by addressing a kernel-level privilege escalation vector, though the immediate impact is more focused on system stability than direct exploitation. Organizations should also consider monitoring network subsystem behavior for unusual routing table modifications or memory allocation patterns that might indicate the presence of this race condition in unpatched systems, as the vulnerability can remain dormant until specific concurrent access patterns are triggered.