CVE-2026-72026 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
irqchip/irq-riscv-imsic-early: Fix fwnode leak on state setup failure
imsic_early_acpi_init() allocates a firmware node before setting up the IMSIC state. If imsic_setup_state() fails, the function returns without freeing the allocated fwnode.
Free the fwnode and clear the global pointer on this error path, matching the cleanup already done when imsic_early_probe() fails.
[ tglx: Use a common cleanup path instead of copying code around ]
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability exists within the Linux kernel's RISC-V interrupt controller implementation, specifically in the irqchip subsystem where the IMSIC (Interrupt Controller for RISC-V) driver handles early initialization. The flaw occurs during the setup process when the imsic_early_acpi_init() function allocates a firmware node structure to represent the interrupt controller's hardware state before attempting to initialize the IMSIC state itself. When the subsequent imsic_setup_state() function encounters an error and fails, the allocated firmware node remains unreleased, creating a memory leak that persists until the system shuts down or the driver is unloaded.
The technical implementation flaw represents a classic resource management error where proper cleanup procedures are not followed during error conditions. The vulnerability manifests as a forward reference to the firmware node structure without corresponding deallocation when the state setup fails, violating fundamental principles of memory management and resource cleanup in kernel space operations. This type of leak can accumulate over time and potentially lead to system instability or resource exhaustion, particularly in embedded systems or virtualized environments where memory is constrained.
From an operational perspective, this vulnerability impacts systems running Linux kernels with RISC-V architecture support, specifically those utilizing ACPI-based interrupt controller initialization paths. The flaw does not directly enable privilege escalation or arbitrary code execution but creates a persistent memory leak that can degrade system performance over time and potentially lead to resource exhaustion attacks in constrained environments where memory allocation failures might trigger cascading system issues. The vulnerability affects the reliability of interrupt handling mechanisms and can impact system responsiveness during sustained operation.
The mitigation approach involves implementing proper error handling with consistent cleanup procedures, ensuring that all allocated resources are freed regardless of whether the initialization process succeeds or fails. This aligns with established security practices found in CWE-459 which addresses improper cleanup of resources, and specifically relates to ATT&CK technique T1486 which covers data destruction through resource exhaustion attacks. The fix implements a common cleanup path that mirrors existing error handling patterns within the same driver codebase, preventing duplicate code while ensuring consistent resource management across all failure scenarios.
This vulnerability demonstrates the importance of robust error handling in kernel space drivers where memory leaks can persist for extended periods and potentially compromise system stability. The fix represents a defensive programming approach that prevents resource leakage by ensuring proper cleanup on all execution paths, including error conditions. The implementation follows established kernel development practices for managing firmware node structures and maintains consistency with other error handling patterns within the same subsystem, reducing the likelihood of similar issues in future developments.