Security update for quagga (important)

This update for quagga fixes the security following issues:

• The Quagga BGP daemon contained a bug in the AS_PATH size calculation
  that could have been exploited to facilitate a remote denial-of-service
  attack via specially crafted BGP UPDATE messages. [CVE-2017-16227,
  bsc#1065641]

• The Quagga BGP daemon did not check whether data sent to peers via
  NOTIFY had an invalid attribute length. It was possible to exploit this
  issue and cause the bgpd process to leak sensitive information over the
  network to a configured peer. [CVE-2018-5378, bsc#1079798]

• The Quagga BGP daemon used to double-free memory when processing certain
  forms of UPDATE messages. This issue could be exploited by sending an
  optional/transitive UPDATE attribute that all conforming eBGP speakers
  should pass along. Consequently, a single UPDATE message could have
  affected many bgpd processes across a wide area of a network. Through
  this vulnerability, attackers could potentially have taken over control
  of affected bgpd processes remotely. [CVE-2018-5379, bsc#1079799]

• It was possible to overrun internal BGP code-to-string conversion tables
  in the Quagga BGP daemon. Configured peers could have exploited this
  issue and cause bgpd to emit debug and warning messages into the logs
  that would contained arbitrary bytes. [CVE-2018-5380, bsc#1079800]

• The Quagga BGP daemon could have entered an infinite loop if sent an
  invalid OPEN message by a configured peer. If this issue was exploited,
  then bgpd would cease to respond to any other events. BGP sessions would
  have been dropped and not be reestablished. The CLI interface would have
  been unresponsive. The bgpd daemon would have stayed in this state until
  restarted. [CVE-2018-5381, bsc#1079801]