In x86's APIC (Advanced Programmable Interrupt Controller) architecture, error conditions are reported in a status register. Furthermore, the OS can opt to receive an interrupt when a new error occurs.

It is possible to configure the error interrupt with an illegal vector, which generates an error when an error interrupt is raised.

This case causes Xen to recurse through vlapic_error(). The recursion itself is bounded; errors accumulate in the the status register and only generate an interrupt when a new status bit becomes set.

However, the lock protecting this state in Xen will try to be taken recursively, and deadlock.

In x86's APIC (Advanced Programmable Interrupt Controller) architecture, error conditions are reported in a status register. Furthermore, the OS can opt to receive an interrupt when a new error occurs.

It is possible to configure the error interrupt with an illegal vector, which generates an error when an error interrupt is raised.

This case causes Xen to recurse through vlapic_error(). The recursion itself is bounded; errors accumulate in the the status register and only generate an interrupt when a new status bit becomes set.

However, the lock protecting this state in Xen will try to be taken recursively, and deadlock.

xen-4.19.0_04-1.1 on GA media

Security update for xen

Affected: Ubuntu:16.04:LTS: xen, Ubuntu:18.04:LTS: xen, Ubuntu:20.04:LTS: xen, Ubuntu:22.04:LTS: xen, Ubuntu:24.04:LTS: xen, Ubuntu:25.10: xen, Ubuntu:26.04:LTS: xen

In x86's APIC (Advanced Programmable Interrupt Controller) architecture, error conditions are reported in a status register. Furthermore, the OS can opt to receive an interrupt when a new error occurs. It is possible to configure the error interrupt with an illegal vector, which generates an error when an error interrupt is raised. This case causes Xen to recurse through vlapic_error(). The recursion itself is bounded; errors accumulate in the the status register and only generate an interrupt when a new status bit becomes set. However, the lock protecting this state in Xen will try to be taken recursively, and deadlock.

Ein entfernter, authentisierter Angreifer kann eine Schwachstelle in XEN, Citrix XenServer und Citrix Systems Hypervisor ausnutzen, um einen Denial of Service Angriff durchzuführen.