CVE-2019-19579

Priority
Description
An issue was discovered in Xen through 4.12.x allowing attackers to gain
host OS privileges via DMA in a situation where an untrusted domain has
access to a physical device (and assignable-add is not used), because of an
incomplete fix for CVE-2019-18424. XSA-302 relies on the use of libxl's
"assignable-add" feature to prepare devices to be assigned to untrusted
guests. Unfortunately, this is not considered a strictly required step for
device assignment. The PCI passthrough documentation on the wiki describes
alternate ways of preparing devices for assignment, and libvirt uses its
own ways as well. Hosts where these "alternate" methods are used will still
leave the system in a vulnerable state after the device comes back from a
guest. An untrusted domain with access to a physical device can DMA into
host memory, leading to privilege escalation. Only systems where guests are
given direct access to physical devices capable of DMA (PCI pass-through)
are vulnerable. Systems which do not use PCI pass-through are not
vulnerable.
Notes
Package
Source: xen (LP Ubuntu Debian)
Upstream:needs-triage
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 19.04 (Disco Dingo):ignored (reached end-of-life)
Ubuntu 19.10 (Eoan Ermine):needs-triage
Ubuntu 20.04 (Focal Fossa):needs-triage
Binaries built from this source package are in universe and so are supported by the community. For more details see https://wiki.ubuntu.com/SecurityTeam/FAQ#Official_Support
More Information

Updated: 2020-01-23 20:49:59 UTC (commit b4629892d998f2ede31f59bb7508dc50a92ac664)