CVE-2022-49768 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
9p: trans_fd/p9_conn_cancel: drop client lock earlier
syzbot reported a double-lock here and we no longer need this lock after requests have been moved off to local list: just drop the lock earlier.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/07/2025
The vulnerability identified as CVE-2022-49768 resides within the Linux kernel's 9p network filesystem implementation, specifically affecting the file descriptor transport layer and connection cancellation mechanisms. This issue manifests as a potential deadlock condition that could compromise system stability and availability. The 9p protocol, also known as the 9th Edition Protocol, serves as a network filesystem interface that enables distributed file access across networked systems, making it a critical component in various server and embedded environments where remote file operations are essential.
The technical flaw stems from improper lock management within the trans_fd and p9_conn_cancel functions of the 9p subsystem. The vulnerability occurs when the client lock is maintained for an extended period beyond its necessary scope, creating a scenario where the same lock could be acquired twice in different execution contexts. This double-lock condition arises from the sequence of operations where requests are moved to a local list but the client lock remains held, preventing other threads from accessing critical sections of code. The synchronization primitive becomes a bottleneck that can lead to thread starvation and system unresponsiveness, particularly under concurrent access scenarios typical in networked environments.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially enabling denial of service conditions that could affect the entire system. When the double-lock occurs, it can cause threads to block indefinitely while waiting for lock acquisition, effectively rendering the 9p filesystem interface unavailable to legitimate users and applications. This condition is particularly concerning in server environments where multiple concurrent connections and file operations are common, as it could cascade into broader system instability. The vulnerability affects systems utilizing the 9p protocol for network filesystem sharing, including virtualization environments, embedded systems, and any infrastructure relying on distributed file access patterns.
Mitigation strategies for CVE-2022-49768 focus on implementing the corrected lock management approach that drops the client lock earlier in the execution flow, specifically after requests have been moved to the local list. This change aligns with the principle of minimizing lock duration and reducing the attack surface for deadlock conditions. The fix addresses the underlying issue by ensuring that locks are released as soon as their protective scope is no longer required, following the principle of least privilege in synchronization. System administrators should prioritize applying the kernel updates that contain this fix, particularly in environments where 9p filesystems are actively used, and monitoring for potential performance improvements or stability enhancements following the patch deployment. The vulnerability demonstrates the importance of careful lock management in concurrent systems and aligns with CWE-362, which addresses race conditions and improper locking mechanisms in software implementations.
This vulnerability relates to the broader category of concurrency issues and synchronization problems that fall under the ATT&CK framework's system binary modifications and privilege escalation techniques. The fix represents a fundamental improvement in resource management that reduces the risk of system-level disruptions. Organizations should consider the patching timeline in relation to their operational security policies, as the vulnerability could be exploited by malicious actors to create persistent denial of service conditions. The resolution of this issue contributes to the overall stability and security posture of Linux-based systems that rely on network filesystem protocols for distributed operations.