Xen

When multiple devices share resources and one of them is to be passed through to a guest, security of the entire system and of respective guests individually cannot really be guaranteed without knowing internals of any of the involved guests. Therefore such a configuration cannot really be security-supported, yet making that explicit was so far missing. Resources the sharing of which is known to be problematic include, but are not limited to - - PCI Base Address Registers (BARs) of multiple devices mapping to the same page (4k on x86), - - INTx lines.

Published: 2024-09-25T10:31:51.154Z
Updated: 2024-09-25T13:24:47.409Z

Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR") for Intel VT-d or Unity Mapping ranges for AMD-Vi. These are typically used for platform tasks such as legacy USB emulation. Since the precise purpose of these regions is unknown, once a device associated with such a region is active, the mappings of these regions need to remain continuouly accessible by the device. In the logic establishing these mappings, error handling was flawed, resulting in such mappings to potentially remain in place when they should have been removed again. Respective guests would then gain access to memory regions which they aren't supposed to have access to.

Published: 2024-09-25T10:31:43.523Z
Updated: 2024-09-25T13:29:33.308Z

An attacker with local access to a system (either through a disk or external drive) can present a modified XFS partition to grub-legacy in such a way to exploit a memory corruption in grub’s XFS file system implementation.

Published: 2023-11-10T16:57:03.311Z
Updated: 2024-09-03T17:29:10.425Z

Closing of an event channel in the Linux kernel can result in a deadlock. This happens when the close is being performed in parallel to an unrelated Xen console action and the handling of a Xen console interrupt in an unprivileged guest. The closing of an event channel is e.g. triggered by removal of a paravirtual device on the other side. As this action will cause console messages to be issued on the other side quite often, the chance of triggering the deadlock is not neglectable. Note that 32-bit Arm-guests are not affected, as the 32-bit Linux kernel on Arm doesn't use queued-RW-locks, which are required to trigger the issue (on Arm32 a waiting writer doesn't block further readers to get the lock).

Published: 2024-01-05T16:30:45.807Z
Updated: 2025-11-04T19:16:37.667Z

A division-by-zero error on some AMD processors can potentially return speculative data resulting in loss of confidentiality. 

Published: 2023-08-08T17:06:30.065Z
Updated: 2024-10-17T14:23:18.239Z