Intercepted I/O operations may deal with less than a full machine
word's worth of data. While read paths had been the subject of earlier
XSAs (and hence have been fixed), at least one write path was found
where the data stored into an internal structure could contain bits
from an uninitialized hypervisor stack slot. A subsequent emulated
read would then be able to retrieve these bits.
A malicious unprivileged x86 HVM guest may be able to obtain sensitive
information from the host or other guests.
All Xen versions are vulnerable.
Only x86 systems are affected. ARM systems are not affected.
Only HVM guests can leverage this vulnerability. PV guests cannot
leverage this vulnerability.
Running only PV guests will avoid this issue.
Created xen tracking bugs for this issue:
Affects: fedora-all [bug 1501391]
Name: the Xen project
Upstream: Roger Pau Monné (Citrix)