Re: [Qemu-devel] [PATCH v4 27/30] vmxnet3: validate interrupt indices coming from guest

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

* Michael S. Tsirkin (mst@redhat.com) wrote:
> From: Dmitry Fleytman <dmitry@daynix.com>
> 
> CVE-2013-4544
> 
> Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
> Reported-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/net/vmxnet3.c | 36 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 34 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
> index 5be807c..a4b5c11 100644
> --- a/hw/net/vmxnet3.c
> +++ b/hw/net/vmxnet3.c
> @@ -52,6 +52,9 @@
>  #define VMXNET3_DEVICE_VERSION    0x1
>  #define VMXNET3_DEVICE_REVISION   0x1
>  
> +/* Number of interrupt vectors for INTx/MSI */
> +#define VMXNET3_MAX_NMSIX_INTRS   (1)

As per Dmitry's reply this is apparently the number of non-MSIX
interrupts; can we change the comment to make this clear.

> +
>  /* Macros for rings descriptors access */
>  #define VMXNET3_READ_TX_QUEUE_DESCR8(dpa, field) \
>      (vmw_shmem_ld8(dpa + offsetof(struct Vmxnet3_TxQueueDesc, field)))
> @@ -1305,6 +1308,34 @@ static bool vmxnet3_verify_intx(VMXNET3State *s, int intx)
>             (pci_get_byte(s->parent_obj.config + PCI_INTERRUPT_PIN) - 1));
>  }
>  
> +static void vmxnet3_validate_interrupt_idx(bool is_msix, int idx)
> +{
> +    int max_ints = is_msix ? VMXNET3_MAX_INTRS : VMXNET3_MAX_NMSIX_INTRS;
> +    if (idx >= max_ints) {
> +        hw_error("Bad interrupt index: %d\n", idx);
> +    }

Can we avoid hw_error here, we're using in this in state load, so I'm
OK at the thought of error_report, but then we should make
this return a bool to say it's failed and bubble this up so
that it just fails the post_load test    like any other bad state load.

Dave

> +}
> +
> +static void vmxnet3_validate_interrupts(VMXNET3State *s)
> +{
> +    int i;
> +
> +    VMW_CFPRN("Verifying event interrupt index (%d)", s->event_int_idx);
> +    vmxnet3_validate_interrupt_idx(s->msix_used, s->event_int_idx);
> +
> +    for (i = 0; i < s->txq_num; i++) {
> +        int idx = s->txq_descr[i].intr_idx;
> +        VMW_CFPRN("Verifying TX queue %d interrupt index (%d)", i, idx);
> +        vmxnet3_validate_interrupt_idx(s->msix_used, idx);
> +    }
> +
> +    for (i = 0; i < s->rxq_num; i++) {
> +        int idx = s->rxq_descr[i].intr_idx;
> +        VMW_CFPRN("Verifying RX queue %d interrupt index (%d)", i, idx);
> +        vmxnet3_validate_interrupt_idx(s->msix_used, idx);
> +    }
> +}
> +
>  static void vmxnet3_activate_device(VMXNET3State *s)
>  {
>      int i;
> @@ -1447,6 +1478,8 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>                 sizeof(s->rxq_descr[i].rxq_stats));
>      }
>  
> +    vmxnet3_validate_interrupts(s);
> +
>      /* Make sure everything is in place before device activation */
>      smp_wmb();
>  
> @@ -2005,7 +2038,6 @@ vmxnet3_cleanup_msix(VMXNET3State *s)
>      }
>  }
>  
> -#define VMXNET3_MSI_NUM_VECTORS   (1)
>  #define VMXNET3_MSI_OFFSET        (0x50)
>  #define VMXNET3_USE_64BIT         (true)
>  #define VMXNET3_PER_VECTOR_MASK   (false)
> @@ -2016,7 +2048,7 @@ vmxnet3_init_msi(VMXNET3State *s)
>      PCIDevice *d = PCI_DEVICE(s);
>      int res;
>  
> -    res = msi_init(d, VMXNET3_MSI_OFFSET, VMXNET3_MSI_NUM_VECTORS,
> +    res = msi_init(d, VMXNET3_MSI_OFFSET, VMXNET3_MAX_NMSIX_INTRS,
>                     VMXNET3_USE_64BIT, VMXNET3_PER_VECTOR_MASK);
>      if (0 > res) {
>          VMW_WRPRN("Failed to initialize MSI, error %d", res);
> -- 
> MST
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK