Messages in this thread Patch in this message | | | From | Simon Haggett <> | Subject | [PATCH 1/1] usb: gadget: Don't attempt to dequeue requests for a disabled USB endpoint on Freescale hardware | Date | Fri, 19 Oct 2012 18:19:26 +0100 |
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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.
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@realvnc.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
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