CVE-2026-98932 in Linux
Summary
by MITRE • 10/23/2026
In the Linux kernel, the following vulnerability has been resolved:
EDAC/altera: Fix use-after-free in error paths
In both altr_edac_a10_device_add() and altr_portb_setup(), the error path freed the dci structure before releasing the devres group. Since the managed single and double bit IRQ handlers use altdev(dci->pvt_info) as their data, an IRQ firing between freeing dci and unregistering the IRQs could dereference the freed memory.
Release the devres group first so the managed IRQs are unregistered before the dci structure is freed.
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Analysis
by VulDB Data Team • 10/24/2026
The vulnerability identified in the Linux kernel's EDAC Altera driver represents a classic use-after-free condition that arises from an incorrect ordering of resource cleanup operations during error handling paths. Specifically, within the functions altr_edac_a10_device_add and altr_portb_setup, the code was freeing the dci structure before releasing the associated devres group. This sequence is critical because the managed interrupt request handlers for single and double bit errors rely on data pointers contained within that very dci structure to operate correctly. When the memory backing this structure is deallocated prematurely, any subsequent access to it constitutes a dereference of freed memory, which can lead to undefined behavior, system crashes, or potentially exploitable conditions depending on how the kernel handles such invalid accesses at runtime.
The technical root cause lies in the interaction between device resource management and interrupt handling mechanisms in the Linux kernel. The devres framework is designed to automatically manage resources associated with a device, ensuring they are released when appropriate. However, if the underlying data structure that these managed resources depend on is freed before the resources themselves are unregistered or cleaned up, a race condition emerges. In this specific scenario, an interrupt could fire in the narrow window between the deallocation of the dci structure and the subsequent unregistering of the IRQs. During this interval, the kernel attempts to execute the ISR using stale pointers that no longer point to valid memory, leading to a use-after-free vulnerability. This type of flaw is particularly dangerous because it can be triggered under specific timing conditions during device initialization or removal errors, making it difficult to reproduce consistently but highly impactful when it occurs.
From an industry standards perspective, this issue aligns with CWE-416, which describes Use After Free vulnerabilities where a pointer is used after its memory has been freed. Furthermore, the operational impact relates to potential denial of service through kernel panics or oops messages if the invalid dereference causes a fault that cannot be handled gracefully. In more severe cases, depending on the architecture and specific memory layout at the time of exploitation, such vulnerabilities can sometimes lead to privilege escalation or arbitrary code execution, although in this context, the primary risk is system stability due to kernel-level crashes. The ATT&CK framework would categorize aspects of this under techniques involving resource manipulation that could disrupt service availability, though it is primarily a reliability and integrity issue rather than an active exploitation vector for attackers unless combined with other flaws.
To mitigate this vulnerability, the fix involves reordering the cleanup operations so that the devres group is released first. This ensures that all managed resources, including the IRQ handlers, are properly unregistered and cleaned up before the dci structure itself is freed from memory. By adhering to this correct sequence, the window of opportunity for a race condition where an interrupt accesses freed memory is eliminated. Developers should ensure that in any error path involving managed resources, dependencies between those resources and their underlying data structures are respected during teardown. This includes verifying that all callbacks, handlers, or pointers dependent on specific allocations are detached before the allocation itself is reclaimed. Such disciplined resource management prevents dangling pointer dereferences and maintains system integrity even when errors occur during complex initialization sequences.