CVE-2026-98227 in Linux
Summary
by MITRE • 10/06/2026
In the Linux kernel, the following vulnerability has been resolved:
memstick: ms_block: destroy io_queue workqueue on removal
msb_init_disk() creates the per-card ordered workqueue msb->io_queue with alloc_ordered_workqueue(). It is torn down with destroy_workqueue() only on the init error path; msb_remove() never destroys it. msb_stop() merely flushes the queue, and neither msb_data_clear() nor put_disk() free it. As a result every card insert/remove cycle leaks the workqueue and its kworker, exhausting kernel memory over repeated cycles.
Destroy the workqueue in msb_remove() after the disk has been removed and the queue drained.
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Analysis
by VulDB Data Team • 10/06/2026
The Linux kernel's memstick subsystem contains a resource management flaw within the block device driver for MemoryStick devices, specifically affecting the initialization and removal lifecycle of per-card I/O queues. The vulnerability stems from an asymmetry in how resources are allocated versus how they are released during normal operational cycles. When a new card is inserted, the function msb_init_disk() invokes alloc_ordered_workqueue to create a dedicated workqueue named io_queue for handling block operations associated with that specific device instance. This allocation consumes kernel memory and creates underlying kworker threads necessary for asynchronous task execution. However, while the code correctly handles cleanup during initialization failures by calling destroy_workqueue in the error path, it fails to perform this critical deallocation when a card is physically removed from the system via msb_remove().
This oversight results in a classic resource leak where each insertion and subsequent removal cycle leaves behind an orphaned workqueue structure and its associated kernel worker threads. Although functions like msb_stop() attempt to manage active tasks by flushing the queue, they do not free the underlying data structures allocated during initialization. Similarly, calls to put_disk or msb_data_clear are insufficient for releasing the memory footprint of the workqueue itself. Over time, as users repeatedly insert and remove MemoryStick cards, these unreleased kernel objects accumulate in system memory. This gradual exhaustion can lead to increased pressure on the kernel's memory allocator, potentially causing performance degradation, allocation failures for other critical subsystems, or even a complete system hang if sufficient memory is consumed by leaked workqueue structures.
From a classification perspective, this issue aligns with CWE-401, which describes missing release of memory after effective usage, and falls under the broader category of resource leaks that can contribute to denial-of-service conditions through resource exhaustion. In terms of adversarial behavior mapping, while typically exploited unintentionally through normal device interaction patterns rather than malicious intent, this flaw represents a weakness in proper lifecycle management that could theoretically be leveraged for local denial-of-service attacks by rapidly cycling device connections to deplete kernel memory resources faster than the system can reclaim them under standard garbage collection or idle conditions.
The remediation involves modifying the msb_remove function to explicitly call destroy_workqueue on the io_queue after ensuring the disk has been properly removed and any pending work items have been drained. This ensures that every allocation performed during device initialization is matched by a corresponding deallocation upon device removal, maintaining memory integrity across repeated hot-plug events. System administrators should apply kernel updates containing this fix to prevent long-term stability issues in environments where MemoryStick devices are frequently connected and disconnected.