linux-kernel - Re: [PATCH 1/2] usb: fix cleanup after failure in hub

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Date:	Tue, 20 Aug 2013 15:51:31 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Krzysztof Mazur <krzysiek@...lesie.net>
cc:	linux-usb@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-kernel@...r.kernel.org>,
	Daniel J Blueman <daniel@...ascale-asia.com>
Subject: Re: [PATCH 1/2] usb: fix cleanup after failure in hub_configure()

On Tue, 20 Aug 2013, Krzysztof Mazur wrote:

> > The second patch can either clean up the port devices by hand, or else 
> > jump to a new label after the line that sets maxchild to 0.
> > Alan Stern
> 
> I think that new label is better, it's equivalent to previous version
> except for ugly rename of original fail label.
> 
> Thanks,
> Krzysiek
> -- >8 --
> Subject: [PATCH 2/2 v2] usb: fail on usb_hub_create_port_device() errors
> 
> Ignoring usb_hub_create_port_device() errors cause later NULL pointer
> deference when uninitialized hub->ports[i] entries are dereferenced
> after port memory allocation error.
> 
> Signed-off-by: Krzysztof Mazur <krzysiek@...lesie.net>
> ---
>  drivers/usb/core/hub.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index affed11..292ffa8 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -1557,10 +1557,15 @@ static int hub_configure(struct usb_hub *hub,
>  	if (hub->has_indicators && blinkenlights)
>  		hub->indicator [0] = INDICATOR_CYCLE;
>  
> -	for (i = 0; i < hdev->maxchild; i++)
> -		if (usb_hub_create_port_device(hub, i + 1) < 0)
> +	for (i = 0; i < hdev->maxchild; i++) {
> +		ret = usb_hub_create_port_device(hub, i + 1);
> +		if (ret < 0) {
>  			dev_err(hub->intfdev,
>  				"couldn't create port%d device.\n", i + 1);
> +			hdev->maxchild = i;
> +			goto fail_keep_maxchild;
> +		}
> +	}
>  
>  	usb_hub_adjust_deviceremovable(hdev, hub->descriptor);
>  
> @@ -1569,6 +1574,7 @@ static int hub_configure(struct usb_hub *hub,
>  
>  fail:
>  	hdev->maxchild = 0;
> +fail_keep_maxchild:
>  	dev_err (hub_dev, "config failed, %s (err %d)\n",
>  			message, ret);
>  	/* hub_disconnect() frees urb and descriptor */

Much better.

Alan Stern

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