CVE-2022-50055 in Linux
Summary
by MITRE • 06/18/2025
In the Linux kernel, the following vulnerability has been resolved:
iavf: Fix adminq error handling
iavf_alloc_asq_bufs/iavf_alloc_arq_bufs allocates with dma_alloc_coherent memory for VF mailbox. Free DMA regions for both ASQ and ARQ in case error happens during configuration of ASQ/ARQ registers. Without this change it is possible to see when unloading interface: 74626.583369: dma_debug_device_change: device driver has pending DMA allocations while released from device [count=32]
One of leaked entries details: [device address=0x0000000b27ff9000] [size=4096 bytes] [mapped with DMA_BIDIRECTIONAL] [mapped as coherent]
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Analysis
by VulDB Data Team • 11/30/2025
The vulnerability identified as CVE-2022-50055 represents a critical memory management issue within the Linux kernel's iavf (Intel Adaptive Virtual Function) driver component. This flaw specifically affects the administration queue error handling mechanism, creating a scenario where DMA memory allocations remain unreleased during driver unloading operations. The vulnerability stems from inadequate cleanup procedures when configuration errors occur during the setup of Admin Send Queues (ASQ) and Admin Receive Queues (ARQ) within the virtual function mailbox system. The root cause lies in the failure to properly free DMA coherent memory regions when error conditions are encountered during the allocation process, leading to persistent memory leaks that can accumulate over time and potentially impact system stability.
The technical implementation of this vulnerability manifests through the iavf_alloc_asq_bufs and iavf_alloc_arq_bufs functions which utilize dma_alloc_coherent for allocating memory regions to facilitate VF mailbox communications. When errors occur during the configuration of ASQ/ARQ registers, the driver fails to execute proper cleanup routines that would free the previously allocated DMA regions for both ASQ and ARQ components. This results in memory fragments remaining allocated even after the driver interface is unloaded, creating what the kernel's DMA debugging subsystem identifies as pending DMA allocations. The specific error message indicates that 32 pending DMA allocations remain unreleased from device 0x0000000b27ff9000, with each allocation measuring 4096 bytes and mapped with DMA_BIDIRECTIONAL flag, demonstrating a clear pattern of resource leakage that can compound over multiple driver reload cycles.
The operational impact of this vulnerability extends beyond simple memory leaks to potentially compromise system reliability and performance in environments utilizing Intel virtualized network functions. The persistent DMA allocations can lead to gradual memory fragmentation and reduced available system resources, particularly concerning systems with limited memory capacity or high driver reload frequency. This issue is particularly concerning in virtualized environments where multiple VFs may be actively managed, as the accumulation of leaked DMA regions can contribute to system instability and performance degradation. The vulnerability also exposes potential security implications through resource exhaustion attacks that could leverage the persistent memory leaks to degrade system performance or create denial of service conditions.
Mitigation strategies for this vulnerability require immediate patch application to the Linux kernel, specifically targeting the iavf driver module to ensure proper error handling and resource cleanup during ASQ/ARQ configuration failures. System administrators should implement comprehensive monitoring of DMA allocation patterns and memory usage trends to detect potential leakage symptoms before they escalate to system stability issues. The fix implements proper error handling that ensures both ASQ and ARQ DMA regions are freed when errors occur during register configuration, addressing the core issue identified in the kernel's DMA debugging subsystem. This remediation aligns with industry best practices for memory management and follows established security principles outlined in CWE-404, which addresses improper resource release or unmanaged resources, and supports ATT&CK framework techniques related to resource exhaustion and system stability compromise through improper resource management. Organizations should prioritize patch deployment across all affected systems and implement routine system health monitoring to prevent accumulation of similar memory leaks in other kernel components.