The sco_sock_recvmsg function in net/bluetooth/sco.c in the Linux kernel before 3.9-rc7 does not initialize a certain length variable, which allows local users to obtain sensitive information from kernel stack memory via a crafted recvmsg or recvfrom system call.
https://lkml.org/lkml/2013/4/14/107
https://github.com/torvalds/linux/commit/c8c499175f7d295ef867335bceb9a76a2c3cdc38
http://www.ubuntu.com/usn/USN-1837-1
http://www.openwall.com/lists/oss-security/2013/04/14/3
http://lists.opensuse.org/opensuse-updates/2013-12/msg00129.html