CVE-2015-2756

Published: 1 April 2015

QEMU, as used in Xen 3.3.x through 4.5.x, does not properly restrict access to PCI command registers, which might allow local HVM guest users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response.

Notes

This is a qemu change which is part of the xen package for the
"traditional" qemu. Trusty and newer only provide qemu traditional as
a backup but by default use the generic qemu from the archive and
Vivid completely drops qemu traditional. So the non-qemut patches in
that XSA need to go into qemu.

Status

References

• http://xenbits.xen.org/xsa/advisory-126.html
• https://ubuntu.com/security/notices/USN-2608-1
• https://www.cve.org/CVERecord?id=CVE-2015-2756
• NVD
• Launchpad
• Debian