linux-kernel - Re: [PATCH 1/1] usb: gadget: Don't attempt to dequeue requests for a disabled USB endpoint on Freescale hardware

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Message-ID: <20121019173718.GA2738@arwen.pp.htv.fi>
Date:	Fri, 19 Oct 2012 20:37:19 +0300
From:	Felipe Balbi <balbi@...com>
To:	Simon Haggett <simon.haggett@...lvnc.com>
CC:	Li Yang <leoli@...escale.com>, Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>,
	<linux-kernel@...r.kernel.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH 1/1] usb: gadget: Don't attempt to dequeue requests for a
 disabled USB endpoint on Freescale hardware

Hi,

On Fri, Oct 19, 2012 at 06:19:26PM +0100, Simon Haggett wrote:
> Some gadget drivers may attempt to dequeue requests for an endpoint that has
> already been disabled. For example, in the UVC gadget driver, uvc_function_set_alt()
> will call usb_ep_disable() when alt setting 0 is selected. When the userspace
> application subsequently issues the VIDIOC_STREAMOFF ioctl, uvc_video_enable()
> invokes usb_ep_dequeue() to ensure that all requests have been cancelled.

bug is on uvc gadget, then. Laurent ?

Also, fsl should be removed from the tree, I'm trying to persuade iMX
folks to use drivers/usb/chipidea instead.

> For the Freescale High Speed Dual-Role USB controller, fsl_ep_dequeue() provides
> the implementation of usb_ep_dequeue(). If this is called for a disabled endpoint,
> a kernel oops will occur when the ep->ep.desc field is dereferenced (by ep_index()).
> fsl_ep_disable() sets this field to NULL, as well as deleting all pending requests
> for the endpoint.
> 
> This patch adds an additional check to fsl_ep_dequeue() to ensure that the
> endpoint has not already been disabled before attempting to dequeue requests.
> 
> Signed-off-by: Simon Haggett <simon.haggett@...lvnc.com>
> ---
>  drivers/usb/gadget/fsl_udc_core.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/usb/gadget/fsl_udc_core.c b/drivers/usb/gadget/fsl_udc_core.c
> index 6ae70cb..acd513b 100644
> --- a/drivers/usb/gadget/fsl_udc_core.c
> +++ b/drivers/usb/gadget/fsl_udc_core.c
> @@ -955,7 +955,10 @@ static int fsl_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
>  	int ep_num, stopped, ret = 0;
>  	u32 epctrl;
>  
> -	if (!_ep || !_req)
> +	/* Ensure that the ep and request are valid, and the ep is not
> +	 * disabled
> +	 */
> +	if (!_ep || !_req || !ep->ep.desc)
>  		return -EINVAL;
>  
>  	spin_lock_irqsave(&ep->udc->lock, flags);
> -- 
> 1.7.4.1
> 

-- 
balbi

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