linux - security update

Several vulnerabilities have been discovered in the Linux kernel that
may lead to a privilege escalation, denial of service or information
leak.

• CVE-2015-7513
  It was discovered that a local user permitted to use the x86 KVM
  subsystem could configure the PIT emulation to cause a denial of
  service (crash).
• CVE-2015-7550
  Dmitry Vyukov discovered a race condition in the keyring subsystem
  that allows a local user to cause a denial of service (crash).
• CVE-2015-8543
  It was discovered that a local user permitted to create raw sockets
  could cause a denial-of-service by specifying an invalid protocol
  number for the socket. The attacker must have the CAP_NET_RAW
  capability.
• CVE-2015-8550
  Felix Wilhelm of ERNW discovered that the Xen PV backend drivers
  may read critical data from shared memory multiple times. This
  flaw can be used by a guest kernel to cause a denial of service
  (crash) on the host, or possibly for privilege escalation.
• CVE-2015-8551 /
  CVE-2015-8552
  Konrad Rzeszutek Wilk of Oracle discovered that the Xen PCI
  backend driver does not adequately validate the device state when
  a guest configures MSIs. This flaw can be used by a guest kernel
  to cause a denial of service (crash or disk space exhaustion) on
  the host.
• CVE-2015-8569
  Dmitry Vyukov discovered a flaw in the PPTP sockets implementation
  that leads to an information leak to local users.
• CVE-2015-8575
  David Miller discovered a flaw in the Bluetooth SCO sockets
  implementation that leads to an information leak to local users.
• CVE-2015-8709
  Jann Horn discovered a flaw in the permission checks for use of
  the ptrace feature. A local user who has the CAP_SYS_PTRACE
  capability within their own user namespace could use this flaw for
  privilege escalation if a more privileged process ever enters that
  user namespace. This affects at least the LXC system.

In addition, this update fixes some regressions in the previous update:

• #808293
  A regression in the UDP implementation prevented freeradius and
  some other applications from receiving data.
• #808602 /
  #808953
  A regression in the USB XHCI driver prevented use of some devices
  in USB 3 SuperSpeed ports.
• #808973
  A fix to the radeon driver interacted with an existing bug to
  cause a crash at boot when using some AMD/ATI graphics cards.
  This issue only affects wheezy.

For the oldstable distribution (wheezy), these problems have been fixed
in version 3.2.73-2+deb7u2. The oldstable distribution (wheezy) is not
affected by CVE-2015-8709.

For the stable distribution (jessie), these problems have been fixed in
version 3.16.7-ckt20-1+deb8u2.
CVE-2015-8543
was already fixed in version 3.16.7-ckt20-1+deb8u1.

For the unstable distribution (sid), these problems have been fixed in
version 4.3.3-3 or earlier.

We recommend that you upgrade your linux packages.