The recently discovered vulnerability in Thunderbolt has restarted discussions about protecting the kernel against untrusted, hotpluggable hardware. That vulnerability, known as Thunderclap, allows a hostile external device to exploit Input-Output Memory Management Unit (IOMMU) mapping limitations and access system memory it was not intended to. Thunderclap can be exploited by USB-C-connected devices; while we have seen USB attacks in the past, this vulnerability is different in that PCI devices, often considered as trusted, can be a source of attacks too. One way of stopping those attacks would be to make sure that the IOMMU is used correctly and restricts the device to accessing the memory that was allocated for it. Lu Baolu has posted an implementation of that approach in the form of bounce buffers for untrusted devices.