crypto/ghash-generic.c in the Linux kernel before 3.1 allows local users to
cause a denial of service (NULL pointer dereference and OOPS) or possibly
have unspecified other impact by triggering a failed or missing
ghash_setkey function call, followed by a (1) ghash_update function call or
(2) ghash_final function call, as demonstrated by a write operation on an
AF_ALG socket.

Nick Bowler discovered the kernel GHASH message digest algorithm
incorrectly handled error conditions. A local attacker could exploit this
to cause a kernel oops.