CVE-2020-15564

An issue was discovered in Xen through 4.13.x, allowing Arm guest OS users
to cause a hypervisor crash because of a missing alignment check in
VCPUOP_register_vcpu_info. The hypercall VCPUOP_register_vcpu_info is used
by a guest to register a shared region with the hypervisor. The region will
be mapped into Xen address space so it can be directly accessed. On Arm,
the region is accessed with instructions that require a specific alignment.
Unfortunately, there is no check that the address provided by the guest
will be correctly aligned. As a result, a malicious guest could cause a
hypervisor crash by passing a misaligned address. A malicious guest
administrator may cause a hypervisor crash, resulting in a Denial of
Service (DoS). All Xen versions are vulnerable. Only Arm systems are
vulnerable. x86 systems are not affected.

Notes