xen - security update

Multiple vulnerabilities have been discovered in the Xen hypervisor. The
Common Vulnerabilities and Exposures project identifies the following
problems:

• CVE-2014-3672 (XSA-180)

Andrew Sorensen discovered that a HVM domain can exhaust the hosts
disk space by filling up the log file.

• CVE-2016-3158 /
  CVE-2016-3159 (XSA-172)

Jan Beulich from SUSE discovered that Xen does not properly handle
writes to the hardware FSW.ES bit when running on AMD64 processors.
A malicious domain can take advantage of this flaw to obtain address
space usage and timing information, about another domain, at a
fairly low rate.

• CVE-2016-3710 (XSA-179)

Wei Xiao and Qinghao Tang of 360.cn Inc discovered an out-of-bounds
read and write flaw in the QEMU VGA module. A privileged guest user
could use this flaw to execute arbitrary code on the host with the
privileges of the hosting QEMU process.

• CVE-2016-3712 (XSA-179)

Zuozhi Fzz of Alibaba Inc discovered potential integer overflow
or out-of-bounds read access issues in the QEMU VGA module. A
privileged guest user could use this flaw to mount a denial of
service (QEMU process crash).

• CVE-2016-3960 (XSA-173)

Ling Liu and Yihan Lian of the Cloud Security Team, Qihoo 360
discovered an integer overflow in the x86 shadow pagetable code. A
HVM guest using shadow pagetables can cause the host to crash. A PV
guest using shadow pagetables (i.e. being migrated) with PV
superpages enabled (which is not the default) can crash the host, or
corrupt hypervisor memory, potentially leading to privilege
escalation.

• CVE-2016-4480 (XSA-176)

Jan Beulich discovered that incorrect page table handling could
result in privilege escalation inside a Xen guest instance.

• CVE-2016-6258 (XSA-182)

JĂŠrĂŠmie Boutoille discovered that incorrect pagetable handling in
PV instances could result in guest to host privilege escalation.

• Additionally this Xen Security Advisory without a CVE was fixed: XSA-166

Konrad Rzeszutek Wilk and Jan Beulich discovered that ioreq handling
is possibly susceptible to a multiple read issue.

For Debian 7 Wheezy, these problems have been fixed in version
4.1.6.lts1-1.

We recommend that you upgrade your xen packages.

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: <https://wiki.debian.org/LTS&gt;