Re: [Xen-devel] [PATCH RFC 1 3/8] xen/pt: Check if reg->init is past the reg->size

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 29 Jun 2015, Konrad Rzeszutek Wilk wrote:
> It should never happen, but in case it does we want to
> report. The code will only write up to reg->size so there
> is no runtime danger.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  hw/xen/xen_pt_config_init.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c
> index 91c3a14..bc871c9 100644
> --- a/hw/xen/xen_pt_config_init.c
> +++ b/hw/xen/xen_pt_config_init.c
> @@ -1901,9 +1901,13 @@ static int 
> xen_pt_config_reg_init(XenPCIPassthroughState *s,
>          } else
>              val = data;
>  
> +        if (val & size_mask) {
> +            XEN_PT_ERR(&s->dev,"Offset 0x%04x:0x%04u expands past register 
> size(%d)!\n",
> +                       offset, val, reg->size);

should we return early?


> +        }
>          /* This could be just pci_set_long as we don't modify the bits
> -         * past reg->size, but in case this routine is run in parallel
> -         * we do not want to over-write other registers. */
> +         * past reg->size, but in case this routine is run in parallel or the
> +         * init value is larger, we do not want to over-write registers. */
>          switch (reg->size) {
>          case 1: pci_set_byte(s->dev.config + offset, (uint8_t)val); break;
>          case 2: pci_set_word(s->dev.config + offset, (uint16_t)val); break;
> -- 
> 2.1.0
> 

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