linux - security update

This update fixes the CVEs described below.

• CVE-2016-3857
  Chiachih Wu reported two bugs in the ARM OABI compatibility layer
  that can be used by local users for privilege escalation. The
  OABI compatibility layer is enabled in all kernel flavours for
  armel and armhf.
• CVE-2016-4470
  Wade Mealing of the Red Hat Product Security Team reported that
  in some error cases the KEYS subsystem will dereference an
  uninitialised pointer. A local user can use the keyctl()
  system call for denial of service (crash) or possibly for
  privilege escalation.
• CVE-2016-5696
  Yue Cao, Zhiyun Qian, Zhongjie Wang, Tuan Dao, and Srikanth V.
  Krishnamurthy of the University of California, Riverside; and Lisa
  M. Marvel of the United States Army Research Laboratory discovered
  that Linux’s implementation of the TCP Challenge ACK feature
  results in a side channel that can be used to find TCP connections
  between specific IP addresses, and to inject messages into those
  connections.

Where a service is made available through TCP, this may allow
remote attackers to impersonate another connected user to the
server or to impersonate the server to another connected user. In
case the service uses a protocol with message authentication
(e.g. TLS or SSH), this vulnerability only allows denial of
service (connection failure). An attack takes tens of seconds, so
short-lived TCP connections are also unlikely to be vulnerable.

This may be mitigated by increasing the rate limit for TCP
Challenge ACKs so that it is never exceeded:
sysctl net.ipv4.tcp_challenge_ack_limit=1000000000

• CVE-2016-5829
  Several heap-based buffer overflow vulnerabilities were found in
  the hiddev driver, allowing a local user with access to a HID
  device to cause a denial of service or potentially escalate their
  privileges.
• CVE-2016-6136
  Pengfei Wang discovered that the audit subsystem has a
  ‘double-fetch’ or TOCTTOU bug in its handling of special
  characters in the name of an executable. Where audit logging of
  execve() is enabled, this allows a local user to generate
  misleading log messages.
• CVE-2016-6480
  Pengfei Wang discovered that the aacraid driver for Adaptec RAID
  controllers has a ‘double-fetch’ or TOCTTOU bug in its
  validation of FIB messages passed through the ioctl() system
  call. This has no practical security impact in current Debian
  releases.
• CVE-2016-6828
  Marco Grassi reported a ‘use-after-free’ bug in the TCP
  implementation, which can be triggered by local users. The
  security impact is unclear, but might include denial of service or
  privilege escalation.
• CVE-2016-7118
  Marcin Szewczyk reported that calling fcntl() on a file descriptor
  for a directory on an aufs filesystem would result in am oops.
  This allows local users to cause a denial of service. This is a
  Debian-specific regression introduced in version 3.2.81-1.

For Debian 7 Wheezy, these problems have been fixed in version
3.2.81-2. This version also fixes a build failure (bug #827561) for
custom kernels with CONFIG_MODULES disabled, a regression in version
3.2.81-1. It also updates the PREEMPT_RT featureset to version
3.2.81-rt117.

For Debian 8 Jessie, CVE-2016-3857 has no impact; CVE-2016-4470 and
CVE-2016-5829 were fixed in linux version 3.16.7-ckt25-2+deb8u3 or
earlier; and the remaining issues are fixed in version 3.16.36-1+deb8u1.

We recommend that you upgrade your linux 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;