Memory leak in the keyctl_join_session_keyring function (security/keys/keyctl.c) in Linux kernel 2.6.29-rc2 and earlier allows local users to cause a denial of service (kernel memory consumption) via unknown vectors related to a "missing kfree."

More... (http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2009-0031)