CVE-2026-64461 in Linux
Summary
by MITRE • 07/25/2026
In the Linux kernel, the following vulnerability has been resolved:
PCI: mediatek: Fix IRQ domain leak when port fails to enable
When mtk_pcie_enable_port() fails, mtk_pcie_port_free() removes the port from pcie->ports and frees the port structure. However, the IRQ domains set up earlier by mtk_pcie_init_irq_domain() are never freed.
Fix this by refactoring mtk_pcie_irq_teardown() into a per-port helper, mtk_pcie_irq_teardown_port(), and calling it from mtk_pcie_setup() when mtk_pcie_enable_port() fails. Since the IRQ teardown must only happen in the probe error path (during resume, child devices may have active MSI mappings and the NOIRQ context prohibits sleeping locks), mtk_pcie_enable_port() is changed to return an error code so callers can distinguish the two paths and act accordingly.
This issue was reported by Sashiko while reviewing the EcoNet EN7528 SoC support series.
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Analysis
by VulDB Data Team • 07/25/2026
The vulnerability in question represents a memory leak within the Linux kernel's PCI subsystem, specifically affecting the MediaTek PCIe driver implementation. This flaw manifests when the mtk_pcie_enable_port() function encounters an error during port initialization, creating a scenario where system resources become permanently unreleased. The core issue stems from improper resource management during error handling paths, where the driver correctly frees the port structure but neglects to clean up associated IRQ domain resources that were previously established through mtk_pcie_init_irq_domain(). This creates a persistent memory leak that can accumulate over time and potentially lead to system instability or resource exhaustion. The vulnerability affects systems utilizing MediaTek SoCs such as the EcoNet EN7528, where PCIe port initialization failures trigger this problematic code path.
The technical implementation flaw lies in the driver's error handling mechanism within the PCIe subsystem's MediaTek support code. When mtk_pcie_enable_port() fails, it correctly executes mtk_pcie_port_free() to remove and free the port structure from the pcie->ports list, but fails to invoke the corresponding IRQ domain cleanup function. The fix involves refactoring the existing mtk_pcie_irq_teardown() function into a per-port helper method called mtk_pcie_irq_teardown_port(). This new helper ensures that IRQ domain resources are properly cleaned up when individual port initialization fails. The solution requires modifying mtk_pcie_enable_port() to return explicit error codes, enabling callers to distinguish between normal operation and error conditions. This approach aligns with established kernel development practices for proper resource cleanup during error scenarios.
The operational impact of this vulnerability extends beyond simple memory leaks to potentially affect system reliability and performance in embedded environments. While the leak may appear minor on a single occurrence, repeated failures during PCIe port initialization can lead to progressive resource consumption that impacts overall system stability. The vulnerability is particularly concerning in automotive or industrial applications where MediaTek SoCs are commonly deployed, as these systems often require long-term stable operation without manual intervention. The issue was identified through code review processes during the development of EcoNet EN7528 SoC support, highlighting the importance of thorough testing and validation in embedded driver development. During normal operation, this vulnerability remains dormant, but becomes active whenever port initialization fails, making it a latent security concern that could be exploited by attackers seeking to cause system instability.
The mitigation strategy focuses on proper resource management during error paths within kernel drivers, following established best practices for memory allocation and deallocation in the Linux kernel. The fix implements a targeted approach by ensuring that IRQ domain cleanup occurs only when necessary, specifically during probe error conditions rather than during resume operations where child device MSI mappings might still be active. This solution prevents potential deadlocks or race conditions that could occur if sleeping locks were attempted during resume operations when NOIRQ context is in effect. The implementation aligns with CWE-404, which addresses improper resource release or cleanup, and follows ATT&CK techniques related to privilege escalation through kernel vulnerabilities. The fix also incorporates proper error code propagation throughout the call stack, ensuring that callers can appropriately handle different execution paths based on return values.
The vulnerability represents a classic example of incomplete error handling in kernel drivers where resource cleanup is not properly synchronized with error conditions. The solution demonstrates the importance of maintaining balanced allocation and deallocation patterns in kernel space, particularly for complex subsystems like PCIe that manage multiple types of resources including memory, IRQ domains, and device structures. By introducing per-port cleanup functions and explicit error code handling, the fix ensures that all allocated resources are properly released regardless of execution path taken during initialization. This approach prevents both memory leaks and potential resource exhaustion issues that could impact system performance or availability in production environments. The resolution also serves as a valuable lesson for kernel developers working with complex hardware subsystems, emphasizing the need for comprehensive error handling that accounts for all possible code paths and their associated resource requirements.