The tty_open function in drivers/tty/tty_io.c in the Linux kernel before 3.1.1 mishandles a driver-lookup failure, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via crafted access to a device file under the /dev/pts directory.
http://rhn.redhat.com/errata/RHSA-2015-1221.html
https://bugzilla.redhat.com/show_bug.cgi?id=1201887
https://github.com/torvalds/linux/commit/c290f8358acaeffd8e0c551ddcc24d1206143376