netdev - Re: [Xen-devel] [PATCH net-next V2] xen-netfront: avoid leaking resources when setup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 20 May 2013 15:24:12 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Wei Liu <wei.liu2@...rix.com>
Cc:	xen-devel@...ts.xen.org, netdev@...r.kernel.org,
	ian.campbell@...rix.com
Subject: Re: [Xen-devel] [PATCH net-next V2] xen-netfront: avoid leaking
 resources when setup_netfront fails

On Mon, May 20, 2013 at 12:05:12PM +0100, Wei Liu wrote:
> We should correctly free related resources (grant ref, memory page, evtchn)
> when setup_netfront fails.

Looks ok to me.
> 
> Signed-off-by: Wei Liu <wei.liu2@...rix.com>
> ---
>  drivers/net/xen-netfront.c |   33 +++++++++++++++++++++------------
>  1 file changed, 21 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index 1db10141..5770e3b 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -1532,40 +1532,49 @@ static int setup_netfront(struct xenbus_device *dev, struct netfront_info *info)
>  	FRONT_RING_INIT(&info->tx, txs, PAGE_SIZE);
>  
>  	err = xenbus_grant_ring(dev, virt_to_mfn(txs));
> -	if (err < 0) {
> -		free_page((unsigned long)txs);
> -		goto fail;
> -	}
> +	if (err < 0)
> +		goto grant_tx_ring_fail;
>  
>  	info->tx_ring_ref = err;
>  	rxs = (struct xen_netif_rx_sring *)get_zeroed_page(GFP_NOIO | __GFP_HIGH);
>  	if (!rxs) {
>  		err = -ENOMEM;
>  		xenbus_dev_fatal(dev, err, "allocating rx ring page");
> -		goto fail;
> +		goto alloc_rx_ring_fail;
>  	}
>  	SHARED_RING_INIT(rxs);
>  	FRONT_RING_INIT(&info->rx, rxs, PAGE_SIZE);
>  
>  	err = xenbus_grant_ring(dev, virt_to_mfn(rxs));
> -	if (err < 0) {
> -		free_page((unsigned long)rxs);
> -		goto fail;
> -	}
> +	if (err < 0)
> +		goto grant_rx_ring_fail;
>  	info->rx_ring_ref = err;
>  
>  	err = xenbus_alloc_evtchn(dev, &info->evtchn);
>  	if (err)
> -		goto fail;
> +		goto alloc_evtchn_fail;
>  
>  	err = bind_evtchn_to_irqhandler(info->evtchn, xennet_interrupt,
>  					0, netdev->name, netdev);
>  	if (err < 0)
> -		goto fail;
> +		goto bind_fail;
>  	netdev->irq = err;
>  	return 0;
>  
> - fail:
> +	/* If we fail to setup netfront, it is safe to just revoke access to
> +	 * granted pages because backend is not accessing it at this point.
> +	 */
> +bind_fail:
> +	xenbus_free_evtchn(dev, info->evtchn);
> +alloc_evtchn_fail:
> +	gnttab_end_foreign_access_ref(info->rx_ring_ref, 0);
> +grant_rx_ring_fail:
> +	free_page((unsigned long)rxs);
> +alloc_rx_ring_fail:
> +	gnttab_end_foreign_access_ref(info->tx_ring_ref, 0);
> +grant_tx_ring_fail:
> +	free_page((unsigned long)txs);
> +fail:
>  	return err;
>  }
>  
> -- 
> 1.7.10.4
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@...ts.xen.org
> http://lists.xen.org/xen-devel
> 
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html