The dev_ifconf function in net/socket.c in the Linux kernel before 3.6 does not initialize a certain structure, which allows local users to obtain sensitive information from kernel stack memory via a crafted application.
http://www.openwall.com/lists/oss-security/2013/03/05/13
http://www.ubuntu.com/usn/USN-1792-1
http://www.ubuntu.com/usn/USN-1798-1
https://github.com/torvalds/linux/commit/43da5f2e0d0c69ded3d51907d9552310a6b545e8