Re: [RFC 1/5] libvhost-user: Add vu_rem_mem_reg input validation

[Raphael Norwitz <raphael.norwitz@nutanix.com>]

On Wed, Jan 05, 2022 at 11:00:35AM +0000, Stefan Hajnoczi wrote:
> On Wed, Dec 15, 2021 at 10:29:48PM +0000, Raphael Norwitz wrote:
> > Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
> > ---
> >  subprojects/libvhost-user/libvhost-user.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c
> > index 787f4d2d4f..573212a83b 100644
> > --- a/subprojects/libvhost-user/libvhost-user.c
> > +++ b/subprojects/libvhost-user/libvhost-user.c
> > @@ -801,6 +801,12 @@ vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
> >      VuDevRegion shadow_regions[VHOST_USER_MAX_RAM_SLOTS] = {};
> >      VhostUserMemoryRegion m = vmsg->payload.memreg.region, *msg_region = &m;
> >  
> > +    if (vmsg->fd_num != 1 ||
> > +        vmsg->size != sizeof(vmsg->payload.memreg)) {
> > +        vu_panic(dev, "VHOST_USER_REM_MEM_REG received multiple regions");
> > +        return true;
> 
> Most vu_panic() callers return false to indicate that a reply does not
> need to be sent. When the return value is true vu_dispatch() sends a
> response, which we don't want.
> 
> Note that vu_dispatch() returns true (success) when the message handler
> function returns false. The success/failure behavior should probably be
> separated from the reply_requested behavior :(.
> 
> Anyway, returning false is probably appropriate here.
>

Ack - I'll fix it in all the patches.

> Stefan