Buffer overflow in the exitcode_proc_write function in arch/um/kernel/exitcode.c in the Linux kernel before 3.12 allows local users to cause a denial of service or possibly have unspecified other impact by leveraging root privileges for a write operation.
http://www.openwall.com/lists/oss-security/2013/11/04/22
http://www.securityfocus.com/bid/63510
https://github.com/torvalds/linux/commit/201f99f170df14ba52ea4c52847779042b7a623b