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

[Peter Maydell]

On 3 December 2013 16:28, Michael S. Tsirkin <address@hidden> 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 <address@hidden>
> Reported-by: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
>  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? If so the version ID
needs to be bumped.

thanks
-- PMM