Red Hat 6: RHSA-2013:0504-02 Low Severity Fix for DHCP Crash Risk

The dhcp packages provide the Dynamic Host Configuration Protocol (DHCP) that allows individual devices on an IP network to get their own network configuration information, including an IP address, a subnet mask, and a broadcast address.
A flaw was found in the way the dhcpd daemon handled the expiration time of IPv6 leases. If dhcpd's configuration was changed to reduce the default IPv6 lease time, lease renewal requests for previously assigned leases could cause dhcpd to crash. (CVE-2012-3955)
This update also fixes the following bugs:
* Prior to this update, the DHCP server discovered only the first IP address of a network interface if the network interface had more than one configured IP address. As a consequence, the DHCP server failed to restart if the server was configured to serve only a subnet of the following IP addresses. This update modifies network interface addresses discovery code to find all addresses of a network interface. The DHCP server can also serve subnets of other addresses. (BZ#803540)
* Prior to this update, the dhclient rewrote the /etc/resolv.conf file with backup data after it was stopped even when the PEERDNS flag was set to "no" before shut down if the configuration file was changed while the dhclient ran with PEERDNS=yes. This update removes the backing up and restoring functions for this configuration file from the dhclient-script. Now, the dhclient no longer rewrites the /etc/resolv.conf file when stopped. (BZ#824622)
All users of DHCP are advised to upgrade to these updated packages, which fix these issues. After installing this update, all DHCP servers will be restarted automatically.