CVE-2026-92481 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
pinctrl: mediatek: free EINT resources on unbind
mtk_eint_do_init() creates an IRQ domain, populates it with a mapping for every EINT line and installs a chained handler on the parent interrupt, but none of these are ever released. This was harmless while the drivers were built-in, but now that they can be built as modules and unbound/rmmod'd it leaves behind a dangling IRQ domain, interrupt mappings whose chip data points at freed memory, and a chained handler that keeps firing into that freed data.
The plain allocations in mtk_eint_do_init() already use the device-managed devm_*() helpers, so tear the remaining resources down the same way: register a devm action that detaches the chained handler, waits for any in-flight handler to finish, disposes of the per-line mappings and removes the IRQ domain. This mirrors the device-managed lifecycle adopted for the GPIO chip and keeps the whole EINT setup self-cleaning on unbind.
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Analysis
by VulDB Data Team • 09/17/2026
The Linux kernel pinctrl driver for MediaTek platforms contains a resource management flaw that results in memory corruption and system instability when the driver is unloaded or rebound. This vulnerability specifically affects the external interrupt controller implementation, where the initialization routine allocates an IRQ domain and establishes mappings for each available EINT line while also installing a chained handler on the parent interrupt source. While this oversight was benign during earlier development phases when drivers were statically compiled into the kernel image, it becomes critical as modern Linux distributions increasingly utilize modular driver architectures that support dynamic loading and unloading via module removal operations.
The core technical flaw lies in the asymmetry of resource lifecycle management within the initialization function. Although standard memory allocations for per-line data structures are correctly handled using device-managed helpers like devm_kzalloc, which automatically free memory upon device detachment, other critical resources remain manually managed and thus never released during unbind operations. Consequently, when a module is removed, the kernel retains references to an IRQ domain that points to freed memory regions. The interrupt mappings retain chip data structures referencing deallocated memory blocks, creating dangling pointers that can lead to use-after-free conditions if accessed by subsequent system events or driver re-initializations.
The operational impact of this vulnerability extends beyond simple resource leaks into active runtime hazards. Because the chained handler remains registered on the parent interrupt line even after the module is unloaded, any incoming interrupts from that source will trigger execution paths pointing to invalid memory addresses. This can result in kernel panics, data corruption within adjacent memory regions, or unpredictable system behavior depending on how quickly the freed memory is reallocated for other purposes. In high-throughput environments where external interrupts are frequent, this race condition between interrupt handling and module unloading poses a significant stability risk that compromises the reliability of the operating system.
To mitigate this vulnerability, developers must ensure complete teardown of all allocated resources during the driver's removal phase. The recommended fix involves registering device-managed actions using devm_add_action_or_reset to handle the cleanup sequence automatically upon device detachment. This process should include detaching the chained handler from the parent interrupt line and utilizing synchronize_irq or equivalent mechanisms to wait for any in-flight interrupt handlers to complete before proceeding with deallocation. Following this, the per-line mappings must be disposed of and the IRQ domain removed using standard kernel APIs such as irq_domain_remove. By aligning the EINT resource lifecycle with the device-managed pattern already adopted for GPIO chips, the driver achieves self-cleaning behavior that prevents dangling references and ensures safe module unloading without manual intervention or risk of memory corruption.
This issue is categorized under CWE-401, which describes a missing release of memory after effective use in an allocation, specifically manifesting here as improper resource cleanup during object destruction. From a threat modeling perspective aligned with the MITRE ATT&CK framework, this vulnerability relates to techniques involving exploitation of software vulnerabilities for denial of service or potential privilege escalation if an attacker can trigger module unloading conditions combined with interrupt flooding. The fix emphasizes robust state management and adherence to kernel coding standards that prioritize automatic resource cleanup through device-managed APIs to eliminate entire classes of use-after-free bugs in modular drivers.