When eptype is USB_ENDPOINT_XFER_CONTROL and pid is TSIZ_SC_MC_PID_SETUP, usb_ep_get() should return the control endpoint. In hw/usb/core.c, the assumed epnum of the control endpoint is 0. When epnum is not 0, usb_ep_get() will crash due to the check assert(pid == USB_TOKEN_IN || pid == USB_TOKEN_OUT).
The description http://www.capital-micro.com/PDF/CME-M7_Family_User_Guide_EN.pdf (18.5.3.4 (14), 18.5.3.4 (10)) a) mentions that the pid is maintained by the host, b) but doesn't mention that whether the epnum should be 0 for the control endpoint. However, usb_ep_get() assumes it is 0. To avoid potential assertion failure in usb_ep_get(), we could enforce epnum to 0 and warn users. Fixes: 153ef1662c3 ("dwc-hsotg (dwc2) USB host controller emulation") Signed-off-by: Qiang Liu <cyruscy...@gmail.com> --- hw/usb/hcd-dwc2.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/usb/hcd-dwc2.c b/hw/usb/hcd-dwc2.c index e1d96ac..65d9d46 100644 --- a/hw/usb/hcd-dwc2.c +++ b/hw/usb/hcd-dwc2.c @@ -636,6 +636,11 @@ static void dwc2_enable_chan(DWC2State *s, uint32_t index) } if (eptype == USB_ENDPOINT_XFER_CONTROL && pid == TSIZ_SC_MC_PID_SETUP) { + if (epnum != 0) { + qemu_log_mask(LOG_GUEST_ERROR, + "epnum should be 0 for the control endpoint\n"); + epnum = 0; + } pid = USB_TOKEN_SETUP; } else { pid = epdir ? USB_TOKEN_IN : USB_TOKEN_OUT; -- 2.7.4