CVE-2022-49020 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
net/9p: Fix a potential socket leak in p9_socket_open
Both p9_fd_create_tcp() and p9_fd_create_unix() will call p9_socket_open(). If the creation of p9_trans_fd fails, p9_fd_create_tcp() and p9_fd_create_unix() will return an error directly instead of releasing the cscoket, which will result in a socket leak.
This patch adds sock_release() to fix the leak issue.
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Analysis
by VulDB Data Team • 01/19/2026
The vulnerability identified as CVE-2022-49020 represents a critical socket leak issue within the Linux kernel's 9P networking implementation. This flaw exists in the file server protocol handling mechanism that enables network file system operations between clients and servers. The 9P protocol, also known as the Plan 9 File Protocol, is a network protocol that provides a uniform interface for accessing files and directories across networked systems, commonly used in distributed computing environments and virtualization platforms. The vulnerability specifically affects the socket management within the kernel's 9P transport layer implementation.
The technical root cause of this vulnerability lies in the improper resource management within the p9_socket_open function and its associated helper functions p9_fd_create_tcp() and p9_fd_create_unix(). When these functions encounter failures during the creation of p9_trans_fd structures, they fail to properly release the allocated socket resources. This occurs because the error handling path does not include a call to sock_release() to clean up the socket that was allocated but not properly closed. The flaw manifests when the p9_fd_create_tcp() and p9_fd_create_unix() functions return errors directly without ensuring that any previously allocated socket resources are freed, creating a resource leak scenario that can accumulate over time.
The operational impact of this vulnerability extends beyond simple resource consumption, as persistent socket leaks can lead to significant system degradation and potential service disruption. In high-traffic environments or long-running systems, the accumulation of leaked sockets can exhaust available file descriptor limits, causing the system to become unresponsive or fail to establish new network connections. This vulnerability particularly affects systems that heavily utilize 9P file sharing mechanisms, such as virtualization platforms using libvirt, container orchestration systems, or distributed storage solutions that depend on the Plan 9 protocol for file access. The issue is classified under CWE-404, which addresses improper resource release or unmanaged resource consumption, and aligns with ATT&CK technique T1499.004 related to network denial of service through resource exhaustion attacks.
The fix implemented in this patch addresses the vulnerability by ensuring proper resource cleanup through the addition of sock_release() calls in the error handling paths of the affected functions. This remediation follows established security practices for resource management and aligns with the principle of least privilege and proper resource cleanup. The solution ensures that when p9_fd_create_tcp() and p9_fd_create_unix() encounter failures, they properly release any allocated socket resources before returning error codes. This approach prevents the accumulation of leaked sockets that could otherwise lead to system instability or resource exhaustion. The patch demonstrates proper defensive programming practices and follows kernel security guidelines for handling resource allocation failures, making it a robust solution that addresses the core issue without introducing additional complexity or performance overhead. The fix maintains backward compatibility while strengthening the kernel's resource management capabilities and preventing potential denial of service conditions through resource exhaustion attacks.