CVE-2022-49226 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
net: asix: add proper error handling of usb read errors
Syzbot once again hit uninit value in asix driver. The problem still the same -- asix_read_cmd() reads less bytes, than was requested by caller.
Since all read requests are performed via asix_read_cmd() let's catch usb related error there and add __must_check notation to be sure all callers actually check return value.
So, this patch adds sanity check inside asix_read_cmd(), that simply checks if bytes read are not less, than was requested and adds missing error handling of asix_read_cmd() all across the driver code.
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Analysis
by VulDB Data Team • 10/21/2025
The vulnerability identified as CVE-2022-49226 resides within the Linux kernel's USB network driver subsystem, specifically affecting the asix driver responsible for managing ethernet devices connected via USB interfaces. This issue represents a classic case of improper error handling in kernel space networking code that can lead to unpredictable behavior and potential security implications. The vulnerability was discovered through automated fuzzing by syzbot, which repeatedly encountered uninitialized value errors in the asix driver implementation, highlighting a fundamental flaw in how USB read operations are managed within the driver's codebase.
The technical root cause of this vulnerability stems from the asix_read_cmd() function which performs USB read operations but fails to properly validate the number of bytes actually read against the requested amount. When USB read requests return fewer bytes than expected, the driver continues processing without proper error detection, leading to uninitialized memory usage and potential information disclosure. This flaw manifests as a condition where the function reads less data than requested by callers, creating a scenario where subsequent code operates on incomplete or uninitialized data structures. The issue is particularly concerning because all USB read operations within the asix driver flow through this single function, making it a critical path for error propagation throughout the driver's functionality.
The operational impact of this vulnerability extends beyond simple functional failures to potentially compromise system security and stability. Uninitialized memory reads can expose sensitive kernel data to user-space processes, creating information leakage opportunities that align with attack patterns described in the attack technique matrix under T1005 (Data from Local System) and T1059 (Command and Scripting Interpreter). The vulnerability could enable attackers to extract kernel memory contents, potentially revealing cryptographic keys, credentials, or other sensitive information. Additionally, the improper error handling could cause driver instability leading to denial of service conditions that affect network connectivity for USB ethernet devices. This vulnerability directly maps to CWE-457 (Use of Uninitialized Variable) and CWE-248 (Uncaught Exception) within the Common Weakness Enumeration framework, representing both uninitialized variable usage and inadequate exception handling in kernel space code.
The mitigation strategy for CVE-2022-49226 involves implementing comprehensive error checking within the asix_read_cmd() function to validate that the number of bytes read matches or exceeds the requested amount. This approach addresses the core issue by adding proper input validation and ensuring that all callers of this function actually check return values through the introduction of __must_check notation. The patch enforces sanity checks that prevent processing of incomplete data reads and ensures that USB-related errors are properly propagated throughout the driver codebase. This remediation aligns with secure coding practices recommended in the Linux kernel security guidelines and helps prevent similar issues across the broader USB networking subsystem. The solution follows the principle of defense in depth by implementing multiple layers of validation while maintaining backward compatibility with existing driver functionality. System administrators should ensure that affected kernel versions are updated to include this patch, particularly in environments where USB ethernet devices are deployed and where kernel memory protection is critical for overall system security posture.