[PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet()

[Mauro Matteo Cascella]

Check the value of mps before it is used as divisor. Since HCCHAR_MPS is guest
controllable, this prevents a malicious/buggy guest from crashing the QEMU
process on the host.

Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
Reported-by: Gaoning Pan <gaoning.pgn@antgroup.com>
Reported-by: Xingwei Lin <linyi.lxw@antfin.com>
---
 hw/usb/hcd-dwc2.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/usb/hcd-dwc2.c b/hw/usb/hcd-dwc2.c
index 97688d21bf..91476fd781 100644
--- a/hw/usb/hcd-dwc2.c
+++ b/hw/usb/hcd-dwc2.c
@@ -324,6 +324,12 @@ babble:
             }
         }
 
+        if (mps == 0) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                    "%s: Bad HCCHAR_MPS set to zero\n", __func__);
+            return;
+        }
+
         tpcnt = actual / mps;
         if (actual % mps) {
             tpcnt++;
-- 
2.26.2