CVE-2026-93162 in Linux
Summary
by MITRE • 09/18/2026
In the Linux kernel, the following vulnerability has been resolved:
crypto: qat - cancel work on re-enable SR-IOV timeout
The QAT reset worker queues SR-IOV reenable work using a work_struct and completion embedded in an on-stack adf_sriov_dev_data. If the completion wait times out, the reset worker can return while device_sriov_wq still holds or executes the stack-backed work item.
Cancel the work on the device_sriov_wq on timeout before the stack frame unwinds.
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Analysis
by VulDB Data Team • 09/18/2026
The Linux kernel cryptographic accelerator driver for Intel QuickAssist Technology contains a critical concurrency flaw related to Single Root I/O Virtualization management during hardware reset operations. This vulnerability arises from improper synchronization between the kernel workqueue subsystem and device-specific state tracking structures, specifically within the context of SR-IOV re-enablement procedures. The issue is rooted in how the QAT driver manages asynchronous tasks using a work_struct structure that relies on completion mechanisms to signal task execution status. When a hardware reset occurs, the system attempts to queue an SR-IOV reenable operation via a dedicated device workqueue named device_sriov_wq. This queued work item utilizes data structures allocated on the kernel stack within the adf_sriov_dev_data object of the calling function.
The core technical flaw involves a race condition triggered by timeout scenarios during the wait for completion signals from the hardware or lower-level drivers. If the waiting process times out, indicating that the SR-IOV reenable operation has not completed successfully within the expected timeframe, the reset worker proceeds to return control to its caller. However, at this point in execution, the work item remains queued on device_sriov_wq and may still be executing or scheduled for future execution by the kernel's scheduler. Because the adf_sriov_dev_data structure containing the completion mechanism is allocated on the stack of the function that initiated the reset worker, returning from that function causes the stack frame to unwind and deallocate this memory region. Consequently, any subsequent access to the work item or its associated data structures by the device_sriov_wq results in a use-after-free condition where kernel code attempts to read or write to memory addresses that are no longer valid or may have been repurposed for other stack allocations.
This vulnerability classifies under CWE-416, Use After Free, and aligns with ATT&CK technique T1059, Command and Scripting Interpreter, if an attacker can leverage the resulting instability to execute arbitrary code through kernel memory corruption. The operational impact of this flaw is severe, as it compromises the integrity of the kernel's virtual memory management subsystem. An attacker who can trigger repeated SR-IOV resets or manipulate timing conditions to induce timeouts may cause a kernel panic leading to system denial of service. More critically, by carefully crafting inputs to control the contents of the freed stack space before they are reused, an attacker could potentially achieve arbitrary code execution with root privileges, thereby gaining full control over the host operating system and any virtual machines utilizing SR-IOV passthrough capabilities through this device.
Mitigation strategies must address both immediate patching requirements and long-term architectural improvements to kernel driver development practices. The primary remediation involves applying vendor-provided security patches that modify the QAT driver code to explicitly cancel pending work items on device_sriov_wq before returning from functions that use stack-allocated data structures for synchronization primitives. This ensures that no dangling pointers remain active in the scheduler's queue after the associated memory has been freed. Administrators should also ensure that SR-IOV configurations are stable and avoid unnecessary reset cycles during normal operation to reduce exposure windows. Furthermore, developers implementing similar drivers should adopt heap allocation for complex state structures involved in asynchronous operations or utilize reference counting mechanisms to prevent premature deallocation of resources still referenced by workqueues. Regular auditing of kernel code against CWE standards helps identify such concurrency flaws before deployment in production environments.