An issue was discovered in Xen through 4.12.x allowing x86 guest OS users
to cause a denial of service (infinite loop) because certain bit iteration
is mishandled. In a number of places bitmaps are being used by the
hypervisor to track certain state. Iteration over all bits involves
functions which may misbehave in certain corner cases: On x86 accesses to
bitmaps with a compile time known size of 64 may incur undefined behavior,
which may in particular result in infinite loops. A malicious guest may
cause a hypervisor crash or hang, resulting in a Denial of Service (DoS).
All versions of Xen are vulnerable. x86 systems with 64 or more nodes are
vulnerable (there might not be any such systems that Xen would run on). x86
systems with less than 64 nodes are not vulnerable.
mdeslaurhypervisor packages are in universe. For
issues in the hypervisor, add appropriate
tags to each section, ex:
Tags_xen: universe-binary
Source: xen (LP Ubuntu Debian)
Ubuntu 12.04 ESM (Precise Pangolin):DNE
Ubuntu 14.04 ESM (Trusty Tahr):DNE
Ubuntu 16.04 LTS (Xenial Xerus):needs-triage
Ubuntu 18.04 LTS (Bionic Beaver):needs-triage
Ubuntu 19.10 (Eoan Ermine):needs-triage
Ubuntu 20.04 (Focal Fossa):not-affected (4.11.3+24-g14b62ab3e5-1ubuntu1)
Binaries built from this source package are in universe and so are supported by the community. For more details see
More Information

Updated: 2020-02-18 14:14:33 UTC (commit c0d61ad7c8b86ba29097cf5accfef1795e5a2080)