CVE-2022-48904 in Linux
Summary
by MITRE • 08/22/2024
In the Linux kernel, the following vulnerability has been resolved:
iommu/amd: Fix I/O page table memory leak
The current logic updates the I/O page table mode for the domain before calling the logic to free memory used for the page table. This results in IOMMU page table memory leak, and can be observed when launching VM w/ pass-through devices.
Fix by freeing the memory used for page table before updating the mode.
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Analysis
by VulDB Data Team • 09/13/2024
The vulnerability identified as CVE-2022-48904 represents a critical memory management flaw within the Linux kernel's IOMMU subsystem, specifically affecting AMD IOMMU implementations. This issue manifests as a memory leak in the I/O page table management mechanism, which is fundamental to virtualization environments utilizing device pass-through capabilities. The vulnerability arises from a logical sequence error in the IOMMU domain management code where the system updates the I/O page table mode before executing the memory cleanup procedures. This improper ordering creates a scenario where allocated memory pages remain unreleased even after the page table mode has been changed, leading to progressive memory consumption that can eventually impact system stability and performance.
The technical root cause of this vulnerability stems from a violation of proper resource management protocols within the kernel's IOMMU driver implementation. When virtual machines are launched with pass-through devices, the system must dynamically allocate and manage I/O page tables to facilitate hardware access between the virtual environment and physical devices. The flaw occurs during domain mode transitions where the kernel's IOMMU subsystem fails to properly sequence its operations, specifically executing the memory deallocation routine before the mode update operation. This violates fundamental principles of resource management and can be categorized under CWE-404, which addresses improper resource release or unbalanced resource management, and also relates to CWE-772, concerning missing release of memory after effective lifetime. The vulnerability directly impacts the AMD IOMMU driver's ability to properly manage memory resources during runtime operations, particularly in virtualized environments where multiple domain transitions occur frequently.
The operational impact of CVE-2022-48904 extends beyond simple memory consumption issues to potentially compromise system stability and virtualization performance. When multiple virtual machines are running with device pass-through capabilities, the memory leak accumulates over time, leading to gradual system performance degradation and potential out-of-memory conditions. This vulnerability is particularly concerning in server environments where virtualization workloads are intensive and sustained, as the memory leak can eventually cause system crashes or require manual intervention to restart affected services. The issue affects the broader ATT&CK framework's privilege escalation and resource exhaustion categories, as it can be leveraged to consume system resources and potentially impact other running processes. Additionally, the vulnerability demonstrates a failure in the kernel's memory management subsystem that could be exploited by malicious actors to create persistent resource exhaustion conditions, making it relevant to ATT&CK technique T1499.001 which covers resource exhaustion via memory consumption.
Mitigation strategies for CVE-2022-48904 require immediate kernel updates to address the memory management ordering issue within the IOMMU subsystem. System administrators should prioritize applying the patched kernel version that corrects the sequence of operations by ensuring memory cleanup occurs before mode updates. The fix implemented in the patch ensures that I/O page table memory is properly released before any mode transitions take place, preventing the accumulation of unreleased memory pages. Organizations running virtualized environments with AMD IOMMU support should conduct thorough testing of the updated kernel to verify that virtual machine operations remain stable and that no regressions have occurred in device pass-through functionality. Additional monitoring should be implemented to track memory usage patterns and detect any residual memory leaks that might occur during domain transitions. The vulnerability serves as a reminder of the critical importance of proper resource management in kernel-level code and highlights the need for comprehensive testing of IOMMU implementations in virtualization environments where device pass-through is utilized.