https://xenbits.xen.org/xsa/advisory-462.html ISSUE DESCRIPTION ================= 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. IMPACT ====== A buggy or malicious HVM or PVH guest can deadlock Xen, leading to a DoS. VULNERABLE SYSTEMS ================== Xen 4.5 and onwards are vulnerable. Xen 4.4 and older are not vulnerable. Only x86 systems running HVM or PVH guests are vulnerable. Architectures other than x86 are not vulnerable. Only HVM or PVH guests can leverage the vulnerability. PV guests cannot leverage the vulnerability. MITIGATION ========== Not running untrusted HVM or PVH VMs will avoid this vulnerability.
The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=d3a1d8ee6118c9078f6bccf9e3043c319193382a commit d3a1d8ee6118c9078f6bccf9e3043c319193382a Author: Tomáš Mózes <hydrapolic@gmail.com> AuthorDate: 2024-10-09 12:01:09 +0000 Commit: Florian Schmaus <flow@gentoo.org> CommitDate: 2024-10-14 07:13:59 +0000 app-emulation/xen: add 4.18.4_pre0, 4.19.1_pre0 Bug: https://bugs.gentoo.org/940632 Signed-off-by: Tomáš Mózes <hydrapolic@gmail.com> Signed-off-by: Florian Schmaus <flow@gentoo.org> app-emulation/xen/Manifest | 3 + app-emulation/xen/xen-4.18.4_pre0.ebuild | 179 +++++++++++++++++++++++++++++++ app-emulation/xen/xen-4.19.1_pre0.ebuild | 179 +++++++++++++++++++++++++++++++ 3 files changed, 361 insertions(+)
