Re: [PATCH 14/14] hw/i386/vmport: Assert vmport initialized before registering commands

[Liran Alon]

On 10/03/2020 11:30, Michael S. Tsirkin wrote:
> On Tue, Mar 10, 2020 at 01:54:11AM +0200, Liran Alon wrote:
> > vmport_register() is also called from other modules such as vmmouse.
> > Therefore, these modules rely that vmport is realized before those call
> > sites. If this is violated, vmport_register() will NULL-deref.
> >
> > To make such issues easier to debug, assert in vmport_register() that
> > vmport is already realized.
> >
> > Reviewed-by: Nikita Leshenko <address@hidden>
> > Signed-off-by: Liran Alon <address@hidden>
>
> Hmm and what does actually make sure it is realized?

port_state global var is only set in vmport_realizefn().

-Liran

> > ---
> >   hw/i386/vmport.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/hw/i386/vmport.c b/hw/i386/vmport.c
> > index 95d4a23ce9ba..659a323e8448 100644
> > --- a/hw/i386/vmport.c
> > +++ b/hw/i386/vmport.c
> > @@ -68,6 +68,8 @@ static VMPortState *port_state;
> >   void vmport_register(VMPortCommand command, VMPortReadFunc *func, void 
> > *opaque)
> >   {
> >       assert(command < VMPORT_ENTRIES);
> > +    assert(port_state);
> > +
> >       trace_vmport_register(command, func, opaque);
> >       port_state->func[command] = func;
> >       port_state->opaque[command] = opaque;
> > --
> > 2.20.1