Re: [PATCH-for-7.0] hw/pvrdma: Protect against buggy or malicious guest driver

[Philippe Mathieu-Daudé]

On 22/3/22 13:27, Marcel Apfelbaum wrote:
> Hi Yuval
>
> On Mon, Mar 21, 2022 at 2:11 PM Yuval Shaia <yuval.shaia.ml@gmail.com> wrote:
> > Guest driver might execute HW commands when shared buffers are not yet
> > allocated.
> > This might happen on purpose (malicious guest) or because some other
> > guest/host address mapping.
> > We need to protect againts such case.

Fixes: CVE-2022-1050

> > Reported-by: Mauro Matteo Cascella <mcascell@redhat.com>
> > Signed-off-by: Yuval Shaia <yuval.shaia.ml@gmail.com>
> > ---
> >   hw/rdma/vmw/pvrdma_cmd.c  | 6 ++++++
> >   hw/rdma/vmw/pvrdma_main.c | 9 +++++----
> >   2 files changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/rdma/vmw/pvrdma_cmd.c b/hw/rdma/vmw/pvrdma_cmd.c
> > index da7ddfa548..89db963c46 100644
> > --- a/hw/rdma/vmw/pvrdma_cmd.c
> > +++ b/hw/rdma/vmw/pvrdma_cmd.c
> > @@ -796,6 +796,12 @@ int pvrdma_exec_cmd(PVRDMADev *dev)
> >
> >       dsr_info = &dev->dsr_info;
> >
> > +    if (!dsr_info->dsr) {
> > +            /* Buggy or malicious guest driver */
> > +            rdma_error_report("Exec command without dsr, req or rsp buffers");
> > +            goto out;
> > +    }
> > +
> >       if (dsr_info->req->hdr.cmd >= sizeof(cmd_handlers) /
> >                         sizeof(struct cmd_handler)) {
> >           rdma_error_report("Unsupported command");
> > diff --git a/hw/rdma/vmw/pvrdma_main.c b/hw/rdma/vmw/pvrdma_main.c
> > index 91206dbb8e..aae382af59 100644
> > --- a/hw/rdma/vmw/pvrdma_main.c
> > +++ b/hw/rdma/vmw/pvrdma_main.c
> > @@ -159,13 +159,13 @@ static void free_dsr(PVRDMADev *dev)
> >       free_dev_ring(pci_dev, &dev->dsr_info.cq, dev->dsr_info.cq_ring_state);
> >
> >       rdma_pci_dma_unmap(pci_dev, dev->dsr_info.req,
> > -                         sizeof(union pvrdma_cmd_req));
> > +                       sizeof(union pvrdma_cmd_req));
> >
> >       rdma_pci_dma_unmap(pci_dev, dev->dsr_info.rsp,
> > -                         sizeof(union pvrdma_cmd_resp));
> > +                       sizeof(union pvrdma_cmd_resp));
> >
> >       rdma_pci_dma_unmap(pci_dev, dev->dsr_info.dsr,
> > -                         sizeof(struct pvrdma_device_shared_region));
> > +                       sizeof(struct pvrdma_device_shared_region));
>
> Nit: the above changes are not related to the patch, maybe drop them?

Yes please.

> Reviewed-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
>
> Thanks,
> Marcel
>
> >       dev->dsr_info.dsr = NULL;
> >   }
> > @@ -249,7 +249,8 @@ static void init_dsr_dev_caps(PVRDMADev *dev)
> >   {
> >       struct pvrdma_device_shared_region *dsr;
> >
> > -    if (dev->dsr_info.dsr == NULL) {
> > +    if (!dev->dsr_info.dsr) {
> > +        /* Buggy or malicious guest driver */
> >           rdma_error_report("Can't initialized DSR");
> >           return;
> >       }
> > --
> > 2.20.1