Re: [PATCH qemu] hw/net/vmxnet3: Remove g_assert_not_reached() when VMXNET3_REG_ICR is written

[Qiang Liu]

Hi,
On Wed, Jun 23, 2021 at 11:23 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2021/6/23 上午10:26, Qiang Liu 写道:
> > From: cyruscyliu <cyruscyliu@gmail.com>
> >
> > A malicious guest user can write VMXNET3_REG_ICR to crash QEMU. This
> > patch remove the g_aasert_not_reached() there and make the access pass.
> >
> > Fixes: 786fd2b0f87 ("VMXNET3 device implementation")
> > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/309
> > Buglink: https://bugs.launchpad.net/qemu/+bug/1913923
> >
> > Signed-off-by: Qiang Liu <cyruscyliu@gmail.com>
>
>
> Do we need to warn about the unimplemented register?
If we remove the case branch, it will go to the default branch which
can warn users if
VMXNET_DEBUG_CB_ENABLED is defined, so there is no need to warn this
unimplemented register. Am I right?
```
vmxnet3_io_bar1_write(...
    default:
        VMW_CBPRN("Unknown Write to BAR1 [%" PRIx64 "] = %" PRIx64 ", size %d",
                  addr, val, size);
        break;
```

> Thanks
>
>
> > ---
> >   hw/net/vmxnet3.c | 7 -------
> >   1 file changed, 7 deletions(-)
> >
> > diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
> > index eff299f629..a388918479 100644
> > --- a/hw/net/vmxnet3.c
> > +++ b/hw/net/vmxnet3.c
> > @@ -1786,13 +1786,6 @@ vmxnet3_io_bar1_write(void *opaque,
> >           vmxnet3_set_variable_mac(s, val, s->temp_mac);
> >           break;
> >
> > -    /* Interrupt Cause Register */
> > -    case VMXNET3_REG_ICR:
> > -        VMW_CBPRN("Write BAR1 [VMXNET3_REG_ICR] = %" PRIx64 ", size %d",
> > -                  val, size);
> > -        g_assert_not_reached();
> > -        break;
> > -
> >       /* Event Cause Register */
> >       case VMXNET3_REG_ECR:
> >           VMW_CBPRN("Write BAR1 [VMXNET3_REG_ECR] = %" PRIx64 ", size %d",
> > --
> > 2.30.2
> >
>