[Qemu-devel] [PATCH 1/2] xhci: fix segfault

[Gerd Hoffmann <kraxel@redhat.com>]

Guest trying to reset a endpoint of a disconnected device resulted in
xhci trying to dereference uport while being NULL, thereby crashing
qemu.  Fix that by adding a check.  Drop unused dev variable while
touching that code bit.

Cc: qemu-stable@nongnu.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/hcd-xhci.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 7cbf813..ff5f681 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -1429,7 +1429,6 @@ static TRBCCode xhci_reset_ep(XHCIState *xhci, unsigned int slotid,
 {
     XHCISlot *slot;
     XHCIEPContext *epctx;
-    USBDevice *dev;
 
     trace_usb_xhci_ep_reset(slotid, epid);
     assert(slotid >= 1 && slotid <= xhci->numslots);
@@ -1465,8 +1464,8 @@ static TRBCCode xhci_reset_ep(XHCIState *xhci, unsigned int slotid,
         ep |= 0x80;
     }
 
-    dev = xhci->slots[slotid-1].uport->dev;
-    if (!dev) {
+    if (!xhci->slots[slotid-1].uport ||
+        !xhci->slots[slotid-1].uport->dev) {
         return CC_USB_TRANSACTION_ERROR;
     }
 
-- 
1.7.9.7