Re: [Qemu-devel] [PATCH 07/23] hw/pci/pcie_aer.c: fix buffer overruns on invalid state load

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Dec 03, 2013 at 06:30:46PM +0000, Peter Maydell wrote:
> On 3 December 2013 16:28, Michael S. Tsirkin <mst@redhat.com> wrote:
> > 4) CVE-2013-4529
> > hw/pci/pcie_aer.c    pcie aer log can overrun the buffer if log_num is
> >                      too large
> >
> > There are two issues in this file:
> > 1. log_max from remote can be larger than on local
> > then buffer will overrun with data coming from state file.
> > 2. log_num can be larger then we get data corrution
> > again with an overflow but not adversary controlled.
> >
> > Fix both issues.
> >
> > Reported-by: Anthony Liguori <anthony@codemonkey.ws>
> > Reported-by: Michael S. Tsirkin <mst@redhat.com>
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  hw/pci/pcie_aer.c | 15 +++++++++++++--
> >  1 file changed, 13 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/pci/pcie_aer.c b/hw/pci/pcie_aer.c
> > index 991502e..92f3f20 100644
> > --- a/hw/pci/pcie_aer.c
> > +++ b/hw/pci/pcie_aer.c
> > @@ -795,15 +795,26 @@ static const VMStateDescription vmstate_pcie_aer_err = {
> >      }
> >  };
> >
> > +static int pcie_aer_state_post_load(void *opaque, int version_id)
> > +{
> > +    PCIEAERLog *s = opaque;
> > +
> > +    if (s->log_num > s->log_max) {
> > +        return -1;
> > +    }
> > +    return 0;
> > +}
> > +
> >  const VMStateDescription vmstate_pcie_aer_log = {
> >      .name = "PCIE_AER_ERROR_LOG",
> >      .version_id = 1,
> >      .minimum_version_id = 1,
> >      .minimum_version_id_old = 1,
> > +    .post_load = pcie_aer_state_post_load,
> >      .fields     = (VMStateField[]) {
> >          VMSTATE_UINT16(log_num, PCIEAERLog),
> > -        VMSTATE_UINT16(log_max, PCIEAERLog),
> > -        VMSTATE_STRUCT_VARRAY_POINTER_UINT16(log, PCIEAERLog, log_num,
> > +        VMSTATE_UINT16_EQUAL(log_max, PCIEAERLog),
> > +        VMSTATE_STRUCT_VARRAY_POINTER_UINT16(log, PCIEAERLog, log_max,
> >                                vmstate_pcie_aer_err, PCIEAERErr),
> >          VMSTATE_END_OF_LIST()
> >      }
> 
> Isn't this a migration compability break?

How is it a break?

> If so the version ID
> needs to be bumped.
> 
> thanks
> -- PMM