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[Qemu-devel] [PATCH v2] usb: drop active assert when pid is invalid


From: Gonglei
Subject: [Qemu-devel] [PATCH v2] usb: drop active assert when pid is invalid
Date: Mon, 15 Feb 2016 21:04:09 +0800

pid can be gotten from uhci device memory in uhci_handle_td(),
so the guest can trigger assert qemu if we get an invalid pid.
And the uhci spec 2.1.2 tells us The Host Controller sets Host
Controller Process Error bit to 1 when it detects a fatal error
and indicates that the Host Controller suffered a consistency
check failure while processing a Transfer Descriptor. An example
of a consistency check failure would be finding an illegal PID
field while processing the packet header portion of the TD.
When this error occurs, the Host Controller clears the Run/Stop
bit in the Command register to prevent further schedule execution.

We'd better to set UHCI_STS_HCPERR and kick an interrupt, but
active assert Qemu, which follow the real hardware's spec.

[Also fixed BZ 1070027]

Signed-off-by: Gonglei <address@hidden>
---
 v2: Clears the Run/Stop bit in the Command register
     to prevent further schedule execution.

 hw/usb/core.c     | 1 -
 hw/usb/hcd-uhci.c | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/usb/core.c b/hw/usb/core.c
index bea5e1e..6fbcf00 100644
--- a/hw/usb/core.c
+++ b/hw/usb/core.c
@@ -716,7 +716,6 @@ struct USBEndpoint *usb_ep_get(USBDevice *dev, int pid, int 
ep)
     if (ep == 0) {
         return &dev->ep_ctl;
     }
-    assert(pid == USB_TOKEN_IN || pid == USB_TOKEN_OUT);
     assert(ep > 0 && ep <= USB_MAX_ENDPOINTS);
     return eps + ep - 1;
 }
diff --git a/hw/usb/hcd-uhci.c b/hw/usb/hcd-uhci.c
index 5ccfb83..ff66397 100644
--- a/hw/usb/hcd-uhci.c
+++ b/hw/usb/hcd-uhci.c
@@ -883,6 +883,7 @@ static int uhci_handle_td(UHCIState *s, UHCIQueue *q, 
uint32_t qh_addr,
         /* invalid pid : frame interrupted */
         uhci_async_free(async);
         s->status |= UHCI_STS_HCPERR;
+        s->cmd &= ~UHCI_CMD_RS;
         uhci_update_irq(s);
         return TD_RESULT_STOP_FRAME;
     }
-- 
1.8.5.2





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