Hello Kevin,
Kevin Wolf <kw...@redhat.com> 于2018年11月2日周五 下午6:54写道：
> Am 02.11.2018 um 02:22 hat Li Qiang geschrieben:
> > Currently, the nvme_cmb_ops mr doesn't check the addr and size.
> > This can lead an oob access issue. This is triggerable in the guest.
> > Add check to avoid this issue.
> >
> > Fixes CVE-2018-16847.
> >
> > Reported-by: Li Qiang <liq...@gmail.com>
> > Reviewed-by: Paolo Bonzini <pbonz...@redhat.com>
> > Signed-off-by: Li Qiang <liq...@gmail.com>
> > ---
> > hw/block/nvme.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> > index fc7dacb..d097add 100644
> > --- a/hw/block/nvme.c
> > +++ b/hw/block/nvme.c
> > @@ -1175,6 +1175,10 @@ static void nvme_cmb_write(void *opaque, hwaddr
> addr, uint64_t data,
> > unsigned size)
> > {
> > NvmeCtrl *n = (NvmeCtrl *)opaque;
> > +
> > + if (addr + size > NVME_CMBSZ_GETSIZE(n->bar.cmbsz)) {
>
> What prevents a guest from moving the device to the end of the address
> space and causing an integer overflow in addr + size?
>
>
This can't happen as the addr can't be any value, it just can be in the
Memory Region n->ctrl_mem defines.
Thanks,
Li Qiang
> If this happens, we still have .max_access_size = 8. The next question is
> then, is NVME_CMBSZ_GETSIZE guaranteed to be at least 8? I suppose yes,
> but do we want to rely on this for security?
Kevin
>
