CVE-2026-98430 in Linux
Summary
by MITRE • 10/15/2026
In the Linux kernel, the following vulnerability has been resolved:
RDMA/efa: Keep admin queues alive while IRQ is registered
The management IRQ handler accesses both the admin completion queue and the async event queue. The driver registered the IRQ before constructing these queues and destroyed them before freeing the IRQ, so the handler's lifetime was not contained by the resources it accesses.
Initialize the queues with interrupts masked, request the IRQ, and then switch to interrupt mode. On removal, reset the device and free the IRQ before destroying the queues. Also reset the device before destroying the queues if IRQ registration fails, because the device already has their DMA addresses.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in the Linux kernel's RDMA/efa driver stems from a critical race condition involving resource initialization and interrupt request handling. Specifically, the management Interrupt Request handler is designed to access both the admin completion queue and the async event queue. In the flawed implementation, the driver registered the IRQ before these queues were fully constructed, creating a window of time where an incoming interrupt could trigger the handler while the targeted memory structures were not yet valid or initialized. This misalignment between resource lifecycle management and interrupt registration means that the lifetime of the interrupt handler was not properly contained by the resources it accesses, leading to potential access violations when hardware interrupts occur prematurely during driver initialization.
From a technical perspective, this flaw represents a classic use-after-free or null-pointer dereference scenario depending on the exact state of memory at the time of the race condition. When an IRQ fires before the queues are ready, the handler attempts to read from or write to invalid memory addresses associated with uninitialized queue structures. This can result in kernel panics, system crashes, or potentially allow for arbitrary code execution if an attacker can influence the timing and content of these interrupts through local privilege escalation or physical access scenarios involving RDMA hardware. The issue highlights a failure in adhering to safe concurrency patterns where shared resources must be fully initialized before exposing them to asynchronous event handlers that may execute at any time once registered with the kernel interrupt subsystem.
The operational impact of this vulnerability includes system instability and potential denial of service for systems relying on EFA-based RDMA connectivity. In cloud environments or high-performance computing clusters, such crashes can lead to significant downtime and data loss if not handled gracefully by higher-level recovery mechanisms. Furthermore, because the driver interacts with hardware via DMA addresses, improper handling during initialization could also expose sensitive memory regions to unintended access patterns, although the primary risk remains system stability due to invalid pointer dereferences. The vulnerability affects systems where the EFA driver is loaded and initialized under conditions that allow interrupts to be asserted before queue construction completes, which can happen in various boot sequences or hotplug scenarios depending on hardware timing characteristics.
To mitigate this issue, the fix implements a strict ordering of operations during both initialization and removal phases. During initialization, the queues are now constructed with interrupts masked, ensuring they are fully populated and valid before any interrupt handling is enabled. The IRQ request is then issued only after queue construction is complete, followed by switching to normal interrupt mode. This ensures that no interrupt can be processed until all required data structures are ready for access. On removal or failure paths, the device is reset and the IRQ is freed before the queues are destroyed. Additionally, if IRQ registration fails, the device is reset prior to queue destruction because the hardware may already hold DMA addresses pointing to those memory regions; failing to reset in this case could leave dangling references that cause issues during subsequent operations. This approach aligns with best practices for driver development as outlined by CWE-362 regarding concurrent execution errors and ensures proper synchronization between resource allocation and interrupt handling mechanisms, reducing the attack surface associated with race conditions in kernel-space drivers.