On Mon, 2017-09-04 at 06:25 -0400, Frediano Ziglio wrote:
> >
> > Although dispatcher_send_message() does not allow you to send a
> > message
> > type that is invalid for a dispatcher, it still makes sense to be
> > defensive in the receiver. Validate that the message type that was
> > read
> > from the socket is in fact a valid message type for this
> > dispatcher.
> > ---
> > server/dispatcher.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/server/dispatcher.c b/server/dispatcher.c
> > index 4e03ea046..965bae8e8 100644
> > --- a/server/dispatcher.c
> > +++ b/server/dispatcher.c
> > @@ -285,6 +285,10 @@ static int
> > dispatcher_handle_single_read(Dispatcher
> > *dispatcher)
> > /* no messsage */
> > return 0;
> > }
> > + if (type >= dispatcher->priv->max_message_type) {
> > + spice_printerr("Invalid message type for this dispatcher:
> > %u",
> > type);
> > + return 0;
> > + }
> > msg = &dispatcher->priv->messages[type];
> > if (read_safe(dispatcher->priv->recv_fd, payload, msg->size,
> > 1) == -1) {
> > spice_printerr("error reading from dispatcher: %d",
> > errno);
>
> This patch looks like not really defensive. The events where this can
> occurs
> in my mind are:
> - physical damage (memory/cpu);
> - memory corruption;
> - file descriptor messing.
> All quite critical. You print an error and return leaving the state
> inconsistent potentially opening the door at any breach.
> I would use a spice_error, process should die.
Yeah, I thought about that. You make a good point. I'll change it.
>
> On the paranoia level I would use an UNLIKELY macro to hint the
> compiler.
>
> Frediano
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