Re: [PATCH 2/2] vdpa: Fix pointer math bug in vdpasim_get_config()

[Jason Wang <jasowang@redhat.com>]

On 2020/4/6 下午10:45, Dan Carpenter wrote:
> If "offset" is non-zero then we end up copying from beyond the end of
> the config because of pointer math.  We can fix this by casting the
> struct to a u8 pointer.
>
> Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> Is it really worth letting people specify the offset?
>
>   drivers/vdpa/vdpa_sim/vdpa_sim.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> index b3c800653056..e03c25765513 100644
> --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> @@ -509,7 +509,7 @@ static void vdpasim_get_config(struct vdpa_device *vdpa, unsigned int offset,
>   	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
>   
>   	if (offset + len < sizeof(struct virtio_net_config))
> -		memcpy(buf, &vdpasim->config + offset, len);
> +		memcpy(buf, (u8 *)&vdpasim->config + offset, len);
>   }
>   
>   static void vdpasim_set_config(struct vdpa_device *vdpa, unsigned int offset,


Acked-by: Jason Wang <jasowang@redhat.com>