Hi folks, I found this bug by my dwc2 fuzzer. It seems that * https://bugs.launchpad.net/qemu/+bug/1907042 * https://bugs.launchpad.net/qemu/+bug/1525123 or * https://gitlab.com/qemu-project/qemu/-/issues/119 * https://gitlab.com/qemu-project/qemu/-/issues/303 have reported similar issues.
Would it be better to consider and fix them together? Best, Qiang On Sun, Jun 27, 2021 at 11:28 AM Qiang Liu <cyruscy...@gmail.com> wrote: > > 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 >