CVE-2026-98264 in Linux
Summary
by MITRE • 10/06/2026
In the Linux kernel, the following vulnerability has been resolved:
ALSA: virtio: reset device before deleting virtqueues
virtsnd_remove() and virtsnd_freeze() delete the virtqueues before resetting the device. del_vqs() frees the vring backing, but does not provide a generic device quiesce operation. In particular, modern virtio-pci keeps enabled queues active until the device is reset.
Reset the device before deleting the virtqueues so it can no longer access the vring memory when that memory is released. This also covers probe failures after DRIVER_OK, which unwind through virtsnd_remove().
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Analysis
by VulDB Data Team • 10/06/2026
The Linux kernel vulnerability identified in the ALSA subsystem's virtio sound driver involves a critical race condition related to device lifecycle management and memory safety. The core technical flaw lies in the sequence of operations performed during device removal or system freeze events. Specifically, within the functions virsnd_remove() and virsnd_freeze(), the implementation deletes virtual queues before resetting the underlying hardware device. This ordering is fundamentally incorrect because the deletion process invokes del_vqs(), which frees the vring backing memory used for data exchange between the guest operating system and the host hypervisor. However, this function does not include a generic mechanism to quiesce or stop the device from accessing that memory region immediately upon queue destruction.
This architectural oversight becomes particularly dangerous with modern virtio-pci implementations. In these configurations, enabled virtual queues remain active at the hardware level until an explicit reset command is issued by the driver. Consequently, if the vring backing memory is freed while the device still holds valid pointers to that physical or virtual address space, the device may continue to perform read and write operations on deallocated memory pages. This scenario creates a classic use-after-free condition where the hardware agent accesses invalid memory locations because the software has already reclaimed those resources without ensuring the hardware has ceased its access patterns.
The operational impact of this vulnerability is severe, as it can lead to system instability or security compromises depending on how the hypervisor handles such illegal memory accesses from the guest device. If the host detects the out-of-bounds access, it may terminate the virtual machine instance abruptly, resulting in a denial of service for all workloads running within that environment. Alternatively, if the hardware silently ignores the invalid address or maps it to safe default pages, data corruption could occur during audio processing tasks. Furthermore, this flaw affects not only standard device removal scenarios but also probe failures that occur after the driver has been marked as ready (DRIVER_OK). In such error paths, the cleanup routine virsnd_remove() is triggered via unwinding mechanisms, exposing the same race condition even when initialization fails partway through the process.
From a vulnerability classification perspective, this issue aligns with CWE-416: Use After Free, where memory is accessed after it has been freed, leading to undefined behavior and potential exploitation vectors such as arbitrary code execution if an attacker can control the contents of the reclaimed memory region before the hardware accesses it. In terms of adversarial tactics, this relates to ATT&CK technique T1499: Endpoint Denial of Service, specifically through resource exhaustion or instability induced by improper driver-hardware synchronization. The vulnerability highlights a common pitfall in virtualized environments where guest drivers must strictly coordinate state transitions with the hypervisor's expectations regarding device readiness and memory mapping validity.
To mitigate this risk, the resolution involves reordering the operations within virsnd_remove() and virsnd_freeze(). The device reset operation must be executed prior to deleting the virtqueues. By resetting the device first, the driver ensures that all hardware queues are disabled and any pending DMA transactions are completed or discarded before the vring backing memory is released. This guarantees that no active component of the virtual sound card can access the freed memory regions. Additionally, this fix addresses edge cases involving probe failures post-DRIVER_OK by ensuring consistent cleanup logic regardless of whether the device was fully operational or partially initialized when removal occurs. System administrators and kernel maintainers should apply patches containing this ordering correction to prevent potential stability issues in Linux-based virtual machines utilizing virtio sound devices.