Re: [PATCH] xen/netback: Fix null-pointer access in netback_uevent

[Jeremy Fitzhardinge <jeremy@goop.org>]

  On 07/29/2010 08:30 AM, Bastian Blank wrote:
> On Thu, Jul 29, 2010 at 02:44:36PM +0100, Ian Campbell wrote:
>> On Thu, 2010-07-29 at 13:42 +0100, Bastian Blank wrote:
>>> Yes, this is included since 2.6.32-15.
>> The patch from<20100529184452.GA18365@wavehammer.waldi.eu.org>?
> Currently the following patch is used. The next test should be if it is
> really necessary to have this much different structures, a quick look
> said: most likely no.

OK, I'll stick it in.  Do you have a complete commit comment?

Thanks,
     J
> diff --git a/drivers/xen/netback/xenbus.c b/drivers/xen/netback/xenbus.c
> index 99831c7..1930f64 100644
> --- a/drivers/xen/netback/xenbus.c
> +++ b/drivers/xen/netback/xenbus.c
> @@ -162,17 +162,11 @@ fail:
>    */
>   static int netback_uevent(struct xenbus_device *xdev, struct kobj_uevent_env *env)
>   {
> -	struct backend_info *be;
> -	struct xen_netif *netif;
> +	struct backend_info *be = dev_get_drvdata(&xdev->dev);
>   	char *val;
>
>   	DPRINTK("netback_uevent");
>
> -	be = dev_get_drvdata(&xdev->dev);
> -	if (!be)
> -		return 0;
> -	netif = be->netif;
> -
>   	val = xenbus_read(XBT_NIL, xdev->nodename, "script", NULL);
>   	if (IS_ERR(val)) {
>   		int err = PTR_ERR(val);
> @@ -187,7 +181,7 @@ static int netback_uevent(struct xenbus_device *xdev, struct kobj_uevent_env *en
>   		kfree(val);
>   	}
>
> -	if (add_uevent_var(env, "vif=%s", netif->dev->name))
> +	if (be&&  be->netif&&  add_uevent_var(env, "vif=%s", be->netif->dev->name))
>   		return -ENOMEM;
>
>   	return 0;
>