CVE-2022-2308 in Linux
Summary
by MITRE • 09/02/2022
A flaw was found in vDPA with VDUSE backend. There are currently no checks in VDUSE kernel driver to ensure the size of the device config space is in line with the features advertised by the VDUSE userspace application. In case of a mismatch, Virtio drivers config read helpers do not initialize the memory indirectly passed to vduse_vdpa_get_config() returning uninitialized memory from the stack. This could cause undefined behavior or data leaks in Virtio drivers.
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Analysis
by VulDB Data Team • 10/11/2022
The vulnerability identified as CVE-2022-2308 resides within the vDPA (virtual Data Path Acceleration) framework when utilizing the VDUSE (Virtual Device for Userspace) backend implementation. This flaw represents a critical security weakness that affects the kernel-level driver responsible for managing virtualized device configurations in hypervisor environments. The issue specifically targets the communication channel between kernel-space VDUSE drivers and userspace VDUSE applications, creating a potential vector for information disclosure and system instability. The vulnerability stems from inadequate validation mechanisms within the kernel driver that govern how device configuration spaces are handled during virtual device initialization and operation.
The technical root cause of this vulnerability manifests as a missing validation check within the VDUSE kernel driver implementation. When a VDUSE userspace application advertises specific device features and configuration space requirements, the kernel driver fails to verify that the actual device configuration space size matches these advertised capabilities. This mismatch condition occurs during the vduse_vdpa_get_config() function call where Virtio driver configuration read helpers attempt to access memory that has not been properly initialized. The absence of proper bounds checking and memory initialization creates a scenario where uninitialized stack memory is returned to the Virtio drivers, potentially exposing sensitive data from kernel memory regions. This flaw operates at the intersection of kernel memory management and virtualization security controls, making it particularly dangerous in multi-tenant cloud environments where isolation is paramount.
The operational impact of CVE-2022-2308 extends beyond simple data leakage to encompass potential system instability and information disclosure vulnerabilities. When uninitialized memory is returned to Virtio drivers, it may contain remnants of previous kernel operations, potentially exposing sensitive information such as cryptographic keys, system credentials, or internal kernel data structures. This behavior creates an attack surface that could be exploited by malicious actors to gain insights into the underlying system architecture, potentially enabling more sophisticated attacks. The vulnerability affects virtualized environments where VDUSE is implemented, including cloud platforms, containerized deployments, and virtual machine management systems that rely on kernel-level device virtualization. The undefined behavior resulting from uninitialized memory access can also lead to system crashes or unexpected operational states that compromise service availability.
From a cybersecurity perspective, this vulnerability aligns with CWE-126 (Buffer Over-read) and CWE-129 (Improper Validation of Array Index) classifications, representing a failure in proper input validation and memory management practices. The flaw maps to ATT&CK technique T1059.001 (Command and Scripting Interpreter: PowerShell) and T1566 (Phishing) through potential exploitation pathways where attackers might leverage the information disclosure for further system compromise. Mitigation strategies should focus on implementing proper size validation checks within the VDUSE kernel driver, ensuring that all device configuration space sizes match advertised features before memory access operations occur. System administrators should prioritize patching affected kernel versions and implementing monitoring for anomalous memory access patterns. The vulnerability also highlights the importance of secure coding practices in kernel-space components and the necessity of thorough validation of all external inputs, particularly in virtualization and device driver implementations. Organizations utilizing vDPA with VDUSE backends must conduct comprehensive security assessments to identify potential exploitation vectors and implement robust memory initialization protocols to prevent similar vulnerabilities from emerging in other kernel components.