CVE-2022-49619 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
net: sfp: fix memory leak in sfp_probe()
sfp_probe() allocates a memory chunk from sfp with sfp_alloc(). When devm_add_action() fails, sfp is not freed, which leads to a memory leak.
We should use devm_add_action_or_reset() instead of devm_add_action().
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 04/17/2025
The vulnerability identified as CVE-2022-49619 represents a critical memory management flaw within the Linux kernel's SFP (Small Form-factor Pluggable) subsystem. This issue specifically affects the sfp_probe() function which handles the initialization and probing of SFP transceivers in network interfaces. The vulnerability stems from improper resource cleanup mechanisms during error conditions, creating a persistent memory leak that can accumulate over time and potentially lead to system instability or performance degradation.
The technical root cause of this vulnerability lies in the improper handling of device management actions within the SFP subsystem. When sfp_probe() executes, it allocates memory using sfp_alloc() to manage SFP transceiver data structures. The function subsequently attempts to register a cleanup action using devm_add_action(), which is designed to ensure proper resource deallocation when the device is removed or during error conditions. However, when devm_add_action() fails to register the cleanup handler, the allocated sfp memory structure is not properly freed, resulting in a memory leak. This failure mode occurs because devm_add_action() returns an error code when it cannot register the cleanup action, but the calling code does not check this return value or implement proper fallback mechanisms to clean up the allocated memory.
The operational impact of this vulnerability extends beyond simple memory consumption issues. As the memory leak accumulates over time, it can lead to progressive system resource exhaustion, particularly in environments with frequent SFP device probing or high network activity. This vulnerability affects systems running Linux kernels that include the affected SFP subsystem code, potentially impacting server environments, network infrastructure devices, and embedded systems that rely on SFP transceivers for network connectivity. The leak can be particularly problematic in resource-constrained environments where memory management is critical for system stability and performance.
The fix implemented for this vulnerability addresses the core issue by replacing devm_add_action() with devm_add_action_or_reset(). This change ensures that when the cleanup action registration fails, the system automatically resets and frees the allocated resources, preventing the memory leak from occurring. The devm_add_action_or_reset() function provides a more robust mechanism for resource management by guaranteeing that cleanup operations will be performed regardless of registration success or failure. This approach aligns with the principle of defensive programming and follows best practices for memory management in kernel space operations.
This vulnerability maps to CWE-401: "Improper Release of Memory Before Removing Last Reference" and demonstrates the importance of proper error handling in kernel subsystems. The issue also relates to ATT&CK technique T1490: "Inhibit System Recovery" through its potential to cause resource exhaustion and system instability. Organizations should prioritize applying the kernel update that includes this fix, particularly in production environments where SFP transceivers are actively used or where system stability is critical. The vulnerability highlights the need for comprehensive testing of error paths in kernel code and demonstrates how seemingly minor resource management issues can have significant operational impacts in production systems.