The br_parse_ip_options function in net/bridge/br_netfilter.c in the Linux kernel before 2.6.39 does not properly initialize a certain data structure, which allows remote attackers to cause a denial of service by leveraging connectivity to a network interface that uses an Ethernet bridge device.
http://www.openwall.com/lists/oss-security/2011/10/28/14
http://ftp.osuosl.org/pub/linux/kernel/v2.6/ChangeLog-2.6.39