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@xxxxxxxxxxx> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
