PCI devices with RMRRs not deassigned correctly Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR"). These are typically used for platform tasks such as legacy USB emulation. If such a device is passed through to a guest, then on guest shutdown the device is not properly deassigned. The IOMMU configuration for these devices which are not properly deassigned ends up pointing to a freed data structure, including the IO Pagetables. Subsequent DMA or interrupts from the device will have unpredictable behaviour, ranging from IOMMU faults to memory corruption.
| Software | From | Fixed in |
|---|---|---|
| debian / debian_linux | 9.0 | 9.0.x |
| fedoraproject / fedora | 33 | 33.x |
| fedoraproject / fedora | 34 | 34.x |
| fedoraproject / fedora | 35 | 35.x |
| xen / xen | 4.13.0 | 4.15.1.x |