CRED: Must initialise the new creds in prepare_kernel_cred()

The newly allocated creds in prepare_kernel_cred() must be initialised
before get_uid() and get_group_info() can access them.  They should be
copied from the old credentials.
Reported-by: Steve Dickson <steved@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/cred.c

@@ -506,6 +506,7 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon)
 	else
 		old = get_cred(&init_cred);
 
+	*new = *old;
 	get_uid(new->user);
 	get_group_info(new->group_info);