net/bridge/br_mdb.c in the Linux kernel before 3.8.4 does not initialize certain structures, which allows local users to obtain sensitive information from kernel memory via a crafted application.
https://github.com/torvalds/linux/commit/c085c49920b2f900ba716b4ca1c1a55ece9872cc
https://bugzilla.redhat.com/show_bug.cgi?id=923652
http://www.openwall.com/lists/oss-security/2013/03/20/1