diff mbox

[01/35] ehci: make idt processing more robust

Message ID 1458581313-19045-2-git-send-email-mdroth@linux.vnet.ibm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Michael Roth March 21, 2016, 5:27 p.m. UTC 
From: Gerd Hoffmann <kraxel@redhat.com>

Make ehci_process_itd return an error in case we didn't do any actual
iso transfer because we've found no active transaction.  That'll avoid
ehci happily run in circles forever if the guest builds a loop out of
idts.

This is CVE-2015-8558.

Cc: qemu-stable@nongnu.org
Reported-by: Qinghao Tang <luodalongde@gmail.com>
Tested-by: P J P <ppandit@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 156a2e4dbffa85997636a7a39ef12da6f1b40254)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 hw/usb/hcd-ehci.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 4e2161b..d07f228 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -1389,7 +1389,7 @@  static int ehci_process_itd(EHCIState *ehci,
 {
     USBDevice *dev;
     USBEndpoint *ep;
-    uint32_t i, len, pid, dir, devaddr, endp;
+    uint32_t i, len, pid, dir, devaddr, endp, xfers = 0;
     uint32_t pg, off, ptr1, ptr2, max, mult;
 
     ehci->periodic_sched_active = PERIODIC_ACTIVE;
@@ -1479,9 +1479,10 @@  static int ehci_process_itd(EHCIState *ehci,
                 ehci_raise_irq(ehci, USBSTS_INT);
             }
             itd->transact[i] &= ~ITD_XACT_ACTIVE;
+            xfers++;
         }
     }
-    return 0;
+    return xfers ? 0 : -1;
 }