fuse: check size of FUSE_NOTIFY_INVAL_ENTRY message

FUSE_NOTIFY_INVAL_ENTRY didn't check the length of the write so the
message processing could overrun and result in a "kernel BUG at
fs/fuse/dev.c:629!"

Reported-by: Han-Wen Nienhuys <hanwenn@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
{
	req->in.h.len = sizeof(struct fuse_in_header) +
		len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
	list_add_tail(&req->list, &fc->pending);
	req->state = FUSE_REQ_PENDING;
	if (!req->waiting) {
		req->waiting = 1;
		atomic_inc(&fc->num_waiting);
	}
	wake_up(&fc->waitq);
	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
}

static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
{
	req->in.h.len = sizeof(struct fuse_in_header) +
		len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
	list_add_tail(&req->list, &fc->pending);
	req->state = FUSE_REQ_PENDING;
	if (!req->waiting) {
		req->waiting = 1;
		atomic_inc(&fc->num_waiting);
	}
	wake_up(&fc->waitq);
	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
}
