CVE-2022-49657 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
usbnet: fix memory leak in error case
usbnet_write_cmd_async() mixed up which buffers need to be freed in which error case.
v2: add Fixes tag v3: fix uninitialized buf pointer
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Analysis
by VulDB Data Team • 03/27/2025
The vulnerability identified as CVE-2022-49657 represents a memory leak within the Linux kernel's usbnet driver subsystem, specifically affecting the usbnet_write_cmd_async() function. This issue demonstrates a critical flaw in resource management where the driver fails to properly handle buffer cleanup during error conditions, leading to persistent memory allocation that cannot be reclaimed by the system. The vulnerability arises from improper buffer management logic that incorrectly determines which memory buffers require deallocation when error scenarios occur during asynchronous command processing.
The technical implementation flaw stems from the usbnet_write_cmd_async() function's inability to correctly identify and free memory buffers in error cases, creating a memory leak condition that can accumulate over time. This improper buffer handling occurs when the function mixes up the logic for determining which specific buffers need cleanup during different error pathways, resulting in memory allocation that remains allocated even after the error condition has been processed. The vulnerability was introduced due to inadequate error handling in the asynchronous command processing mechanism of the usbnet driver, which is responsible for managing network communication over usb interfaces.
The operational impact of this memory leak vulnerability extends beyond simple resource consumption, as it can lead to progressive system degradation and potential system instability. When the usbnet driver encounters error conditions during asynchronous command processing, the leaked memory accumulates with each occurrence, eventually consuming significant portions of available system memory. This can result in reduced system performance, application crashes, or in severe cases, complete system hangs or reboots, particularly in embedded systems or devices with limited memory resources. The vulnerability affects systems running Linux kernel versions where the usbnet driver is utilized for usb network interface management.
Mitigation strategies for CVE-2022-49657 involve applying the official kernel patch that corrects the buffer management logic within usbnet_write_cmd_async(), ensuring that all allocated buffers are properly freed during error conditions. System administrators should prioritize updating to kernel versions that include the fix, typically kernel versions 5.19 and later where the vulnerability has been resolved. Additionally, monitoring system memory usage and implementing automated alerting for memory consumption patterns can help detect potential exploitation of this vulnerability. The fix addresses the root cause by properly implementing buffer cleanup logic and includes validation to prevent uninitialized buffer pointer issues that could compound the memory leak condition.
This vulnerability aligns with CWE-401, which specifically addresses memory leaks in software systems, and demonstrates a classic example of improper resource management that can be exploited to consume system resources over time. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of a resource exhaustion attack pattern, potentially leading to denial of service conditions that impact system availability. The remediation process involves standard kernel update procedures, but the vulnerability highlights the importance of proper error handling and resource management in kernel-level drivers, particularly those handling asynchronous operations where buffer cleanup must be deterministic and comprehensive.