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

[Michael S. Tsirkin]

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?

> ---
>  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