Multiple issues exist with the setup of PCI MSI interrupts:
- - unprivileged guests were permitted access to devices not owned by
them, in particular allowing them to disable MSI or MSI-X on any
- - HVM guests can trigger a codepath intended only for PV guests
- - some failure paths partially tear down previously configured
interrupts, leaving inconsistent state
- - with XSM enabled, caller and callee of a hook disagreed about the
data structure pointed to by a type-less argument
A malicious or buggy guest may cause the hypervisor to crash, resulting
in Denial of Service (DoS) affecting the entire host. Privilege
escalation and information leaks cannot be excluded.
All Xen versions from at 3.3 onwards are vulnerable. Xen versions 3.2
and earlier are not vulnerable.
Only x86 systems are affected. ARM systems are not affected.
Only guests which have a physical device assigned to them can exploit
Not passing through physical devices to untrusted guests will avoid
The vulnerability can be avoided if the guest kernel is controlled by
the host rather than guest administrator, provided that further steps
are taken to prevent the guest administrator from loading code into the
kernel (e.g. by disabling loadable modules etc) or from using other
mechanisms which allow them to run code at kernel privilege.
Created xen tracking bugs for this issue:
Affects: fedora-all [bug 1501391]
Name: the Xen project
Upstream: Simon Gaiser (Qubes OS)