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.
https://www.kernel.org/pub/linux/kernel/v3.x/patch-3.12.bz2
http://www.securityfocus.com/bid/63510