usb: cdns3: fix memory double free when handle zero packet

In the Linux kernel, the following vulnerability has been resolved: usb: cdns3: fix memory double free when handle zero packet 829 if (request->complete) { 830 spin_unlock(&priv_dev->lock); 831 usb_gadget_giveback_request(&priv_ep->endpoint, 832 request); 833 spin_lock(&priv_dev->lock); 834 } 835 836 if (request->buf == priv_dev->zlp_buf) 837 cdns3_gadget_ep_free_request(&priv_ep->endpoint, request); Driver append an additional zero packet request when queue a packet, which length mod max packet size is 0. When transfer complete, run to line 831, usb_gadget_giveback_request() will free this requestion. 836 condition is true, so cdns3_gadget_ep_free_request() free this request again. Log: [ 1920.140696][ T150] BUG: KFENCE: use-after-free read in cdns3_gadget_giveback+0x134/0x2c0 [cdns3] [ 1920.140696][ T150] [ 1920.151837][ T150] Use-after-free read at 0x000000003d1cd10b (in kfence-#36): [ 1920.159082][ T150] cdns3_gadget_giveback+0x134/0x2c0 [cdns3] [ 1920.164988][ T150] cdns3_transfer_completed+0x438/0x5f8 [cdns3] Add check at line 829, skip call usb_gadget_giveback_request() if it is additional zero length packet request. Needn't call usb_gadget_giveback_request() because it is allocated in this driver.