CVE-2022-48775 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
Drivers: hv: vmbus: Fix memory leak in vmbus_add_channel_kobj
kobject_init_and_add() takes reference even when it fails. According to the doc of kobject_init_and_add()：
If this function returns an error, kobject_put() must be called to properly clean up the memory associated with the object.
Fix memory leak by calling kobject_put().
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Analysis
by VulDB Data Team • 10/27/2024
The vulnerability CVE-2022-48775 represents a memory leak in the Linux kernel's Hyper-V vmbus driver component that specifically affects the vmbus_add_channel_kobj function. This issue occurs within the hypervisor virtualization framework where the kernel manages communication channels between the host and guest operating systems. The flaw manifests when the kobject_init_and_add() function encounters an error condition but fails to properly release the allocated memory resources, leading to a gradual consumption of system memory over time.
The technical root cause stems from improper error handling within the kernel's object management subsystem where the kobject_init_and_add() function does not consistently release memory allocations when it returns an error status. This function is designed to initialize and add kernel objects to the object hierarchy while maintaining proper reference counting and memory management. However, in the affected code path, when kobject_init_and_add() fails to complete its operation successfully, it leaves behind allocated memory structures that should be cleaned up through proper kernel object management protocols.
This memory leak vulnerability directly impacts system stability and performance by consuming available memory resources without proper cleanup. The operational impact extends beyond simple memory consumption as it can lead to system degradation, potential denial of service conditions, and reduced overall system responsiveness. The vulnerability affects systems running Linux kernels with Hyper-V integration components where vmbus channel management is actively utilized, particularly in virtualized environments where multiple channels may be established and torn down frequently.
The fix for CVE-2022-48775 implements proper error handling by ensuring that kobject_put() is called whenever kobject_init_and_add() returns an error. This approach aligns with established kernel development practices and follows the documented API behavior where error conditions must be properly cleaned up to prevent resource leaks. The mitigation strategy directly addresses the fundamental flaw in the kernel's memory management for virtual channel objects and ensures that all allocated resources are properly released regardless of the function's success or failure state. This fix conforms to the principles outlined in the Linux kernel coding standards and follows the recommended practices for kernel object lifecycle management as defined in the kernel documentation and security guidelines.
From a cybersecurity perspective, this vulnerability represents a low-severity memory leak that could potentially be exploited in resource exhaustion scenarios, particularly in systems with limited memory capacity or in environments where multiple virtual channels are actively managed. The vulnerability does not present immediate exploitation vectors but could contribute to system instability and performance degradation over time. Security practitioners should consider this fix as part of routine kernel maintenance and patch management processes, especially in virtualized environments where Hyper-V integration is utilized. The issue demonstrates the importance of proper error handling and resource cleanup in kernel space code, aligning with common weakness enumerations such as CWE-404 (Improper Resource Release or Leaking of Resources) and may be categorized under ATT&CK techniques related to system resource exhaustion and kernel-level persistence mechanisms.