linux-kernel - Re: 2.6.33 bugs (USBFS, Intel graphic)

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Date:	Tue, 2 Mar 2010 16:09:38 -0800
From:	Greg KH <greg@...ah.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Markus Rechberger <mrechberger@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-usb@...r.kernel.org, werner@...ane.dyn-o-saur.com,
	Marcus Meissner <meissner@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: 2.6.33 bugs (USBFS, Intel graphic)

On Sat, Feb 27, 2010 at 12:20:35PM -0500, Alan Stern wrote:
> On Fri, 26 Feb 2010, Greg KH wrote:
> 
> > Hm, so it's back to the original idea of just doing a kzalloc of the
> > initial buffer, that should solve the problem that Marcus found.
> > 
> > I'll go dig that back up and if you could test it, that would be most
> > appreciated.
> 
> Here's a better solution.  In theory we could copy just the individual 
> packets from within the transfer buffer, but that would probably take 
> longer than simply copying the whole buffer.
> 
> (This was a little hasty; I haven't even compile-tested the patch. 
> Some small fixes may be needed.)

Markus, did you test this patch out?

thanks,

greg k-h

> -----------------------------------------------------------------------
> 
> This patch fixes a bug in the way isochronous input data is returned
> to userspace for usbfs transfers.  The entire buffer must be copied,
> not just the first actual_length bytes, because the individual packets
> will be discontiguous if any of them are short.
> 
> Signed-off-by: Alan Stern <stern@...land.harvard.edu>
> CC: stable <stable@...nel.org>
> 
> ---
> 
> Index: usb-2.6/drivers/usb/core/devio.c
> ===================================================================
> --- usb-2.6.orig/drivers/usb/core/devio.c
> +++ usb-2.6/drivers/usb/core/devio.c
> @@ -1176,6 +1176,13 @@ static int proc_do_submiturb(struct dev_
>  			free_async(as);
>  			return -ENOMEM;
>  		}
> +		/* Isochronous input data may end up being discontiguous
> +		 * if some of the packets are short.  Clear the buffer so
> +		 * that the gaps don't leak kernel data to userspace.
> +		 */
> +		if (is_in && uurb->type == USBDEVFS_URB_TYPE_ISO)
> +			memset(as->urb->transfer_buffer, 0,
> +					uurb->buffer_length);
>  	}
>  	as->urb->dev = ps->dev;
>  	as->urb->pipe = (uurb->type << 30) |
> @@ -1312,10 +1319,14 @@ static int processcompl(struct async *as
>  	void __user *addr = as->userurb;
>  	unsigned int i;
>  
> -	if (as->userbuffer && urb->actual_length)
> -		if (copy_to_user(as->userbuffer, urb->transfer_buffer,
> -				 urb->actual_length))
> +	if (as->userbuffer && urb->actual_length) {
> +		if (urb->number_of_packets > 0)		/* Isochronous */
> +			i = urb->transfer_buffer_length;
> +		else					/* Non-Isoc */
> +			i = urb->actual_length;
> +		if (copy_to_user(as->userbuffer, urb->transfer_buffer, i))
>  			goto err_out;
> +	}
>  	if (put_user(as->status, &userurb->status))
>  		goto err_out;
>  	if (put_user(urb->actual_length, &userurb->actual_length))
--
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