CVE-2022-48656 in Linux
Summary
by MITRE • 04/28/2024
In the Linux kernel, the following vulnerability has been resolved:
dmaengine: ti: k3-udma-private: Fix refcount leak bug in of_xudma_dev_get()
We should call of_node_put() for the reference returned by of_parse_phandle() in fail path or when it is not used anymore. Here we only need to move the of_node_put() before the check.
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Analysis
by VulDB Data Team • 05/30/2024
The vulnerability CVE-2022-48656 represents a memory management issue within the Linux kernel's DMA engine subsystem, specifically affecting the ti k3-udma driver implementation. This flaw manifests as a reference count leak in the of_xudma_dev_get() function, which is part of the device tree parsing mechanism used to configure DMA devices in Texas Instruments K3 SoC platforms. The issue occurs during the initialization and configuration process of DMA channels where device tree nodes are parsed and referenced to establish proper hardware communication paths.
The technical root cause stems from improper handling of device tree node references obtained through the of_parse_phandle() function call. When the function successfully retrieves a device tree node reference, it increments the reference count to ensure the node remains valid during the parsing operation. However, in error handling paths or when the reference is no longer needed, the code fails to properly decrement this reference count through the of_node_put() function call. This creates a situation where device tree nodes remain referenced indefinitely, leading to memory leaks that can accumulate over time and potentially impact system stability.
This vulnerability directly relates to CWE-404, which describes improper resource management where resources are not properly released or freed, and specifically addresses the improper handling of reference counting mechanisms in device tree parsing operations. The operational impact of this reference leak can manifest as gradual memory consumption increases within the kernel's device tree management subsystem, potentially leading to system performance degradation or memory exhaustion under sustained load conditions. The flaw is particularly concerning in embedded systems or real-time applications where memory resources are constrained and predictable behavior is critical.
The mitigation strategy involves ensuring proper reference count management by moving the of_node_put() call to occur before any conditional checks that might exit the function early. This approach aligns with the ATT&CK framework's defensive techniques for resource management and kernel-level memory protection. The fix requires careful code restructuring to ensure that every reference obtained through of_parse_phandle() is properly balanced with an of_node_put() call regardless of execution path, maintaining proper resource lifecycle management throughout the function's operation.
The vulnerability demonstrates the critical importance of proper reference counting in kernel space programming where resource leaks can have cascading effects on system stability and performance. Device tree parsing operations are fundamental to modern embedded systems configuration, making this flaw particularly significant for Texas Instruments K3 platform deployments. The fix implementation emphasizes defensive programming practices that prevent resource leaks through careful management of kernel object references, ensuring that all allocated resources are properly accounted for and released. This type of vulnerability underscores the need for comprehensive testing of error paths and resource management in kernel subsystems, particularly those involving device tree parsing and hardware abstraction layers that are critical to system operation.