Linux kernel (drivers/pci): The DOE state machine signals the caller's completion before destroying the work_struct

Impact

The DOE state machine signals the caller's completion before destroying the work_struct that lives on the caller's stack, so the workqueue can still be touching a stack frame the caller has already left. DOE is the mailbox that carries CMA/SPDM device attestation and IDE link-encryption negotiation, which makes this a race in exactly the machinery a confidential-GPU deployment relies on to decide whether a device is trustworthy.

Who can reach it

Host-side only, on nodes where a device exposes a DOE mailbox and something drives it - CXL, device attestation (CMA/SPDM), or IDE key exchange. There is no tenant-facing entry point: the race is between the DOE workqueue and the kernel thread that submitted the task, and its timing is influenced by how slowly the device answers, so a slow or deliberately laggy device shifts the window. Nodes with no DOE-capable device, or with attestation/IDE unused, never execute the path.

What to do

Update to 6.1.53 / 6.3 or later, where the work struct is destroyed before the completion is signalled. Interim: on affected kernels avoid driving DOE in production - leave CMA/SPDM attestation and IDE negotiation disabled until patched rather than running them against untrusted devices.

References