Re: [Qemu-devel] [PATCH v4 10/30] hw/pci/pcie_aer.c: fix buffer overruns on invalid state load

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* 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 corruption
> 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>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  hw/pci/pcie_aer.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/pci/pcie_aer.c b/hw/pci/pcie_aer.c
> index 991502e..535be2c 100644
> --- a/hw/pci/pcie_aer.c
> +++ b/hw/pci/pcie_aer.c
> @@ -795,6 +795,13 @@ static const VMStateDescription vmstate_pcie_aer_err = {
>      }
>  };
>  
> +static bool pcie_aer_state_log_num_valid(void *opaque, int version_id)
> +{
> +    PCIEAERLog *s = opaque;
> +
> +    return s->log_num <= s->log_max;
> +}
> +
>  const VMStateDescription vmstate_pcie_aer_log = {
>      .name = "PCIE_AER_ERROR_LOG",
>      .version_id = 1,
> @@ -802,7 +809,8 @@ const VMStateDescription vmstate_pcie_aer_log = {
>      .minimum_version_id_old = 1,
>      .fields     = (VMStateField[]) {
>          VMSTATE_UINT16(log_num, PCIEAERLog),
> -        VMSTATE_UINT16(log_max, PCIEAERLog),
> +        VMSTATE_UINT16_EQUAL(log_max, PCIEAERLog),
> +        VMSTATE_VALIDATE("log_num <= log_max", pcie_aer_state_log_num_valid),
>          VMSTATE_STRUCT_VARRAY_POINTER_UINT16(log, PCIEAERLog, log_num,
>                                vmstate_pcie_aer_err, PCIEAERErr),
>          VMSTATE_END_OF_LIST()
> -- 
> MST
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK