security: introduce missing kfree

Plug this leak.
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: <stable@kernel.org>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

security/keys/keyctl.c

@@ -270,6 +270,7 @@ long keyctl_join_session_keyring(const char __user *_name)
 
 	/* join the session */
 	ret = join_session_keyring(name);
+	kfree(name);
 
  error:
 	return ret;