Univention Corporate Server 4.1 erratum 74 (security)

The Linux kernel in Univention Corporate Server 4.1 has been updated to
4.1.16. It provides many bugfixes and fixes several vulnerabilities:
* Use-after-free vulnerability in net/unix/af_unix.c allows local users to
  bypass intended AF_UNIX socket permissions or cause a denial of service
  (panic) via crafted epoll_ctl calls (CVE-2013-7446)
* virtio-net: drop NETIF_F_FRAGLIST (CVE-2015-5156)
* [x86] KVM: Intercept #AC to avoid guest->host denial-of-service
  (CVE-2015-5307)
* RDS: verify the underlying transport exists before creating a connection
  (CVE-2015-6937)
* RDS: fix race condition when sending a message on unbound socket
  (CVE-2015-7990)
* fs/btrfs/inode.c mishandles compressed inline extents, which allows local
  users to obtain sensitive pre-truncation information from a file via a
  clone action (CVE-2015-8374)
* usb: serial: visor: fix crash on detecting device without write_urbs
  (CVE-2015-7566)
* tty: Fix unsafe ldisc reference via ioctl(TIOCGETD) (CVE-2016-0723)
* unix: properly account for FDs passed over unix sockets (CVE-2013-4312)
* keyring ref leak in join_session_keyring() (CVE-2016-0728)
* KEYS: Fix race between read and revoke (CVE-2015-7550)
* net: add validation for the socket syscall protocol argument
  (CVE-2015-8543)
* bluetooth: Validate socket address length in sco_sock_bind()
  (CVE-2015-8575)
* KEYS: Fix crash when attempt to garbage collect an uninstantiated keyring
  (CVE-2015-7872)
* pptp: verify sockaddr_len in pptp_bind() and pptp_connect() (CVE-2015-8569)