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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Mon, 14 Dec 2015 09:21:23 +0100
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Subject: [PATCH] ehci: make idt processing more robust
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Make ehci_process_itd return an error in case we didn't do any actual
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iso transfer because we've found no active transaction. That'll avoid
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ehci happily run in circles forever if the guest builds a loop out of
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idts.
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This is CVE-2015-8558.
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Cc: qemu-stable@nongnu.org
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Reported-by: Qinghao Tang <luodalongde@gmail.com>
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Tested-by: P J P <ppandit@redhat.com>
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit 156a2e4dbffa85997636a7a39ef12da6f1b40254)
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---
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hw/usb/hcd-ehci.c | 5 +++--
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1 file changed, 3 insertions(+), 2 deletions(-)
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diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
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index 4e2161b..d07f228 100644
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--- a/hw/usb/hcd-ehci.c
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+++ b/hw/usb/hcd-ehci.c
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@@ -1389,7 +1389,7 @@ static int ehci_process_itd(EHCIState *ehci,
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{
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USBDevice *dev;
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USBEndpoint *ep;
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- uint32_t i, len, pid, dir, devaddr, endp;
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+ uint32_t i, len, pid, dir, devaddr, endp, xfers = 0;
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uint32_t pg, off, ptr1, ptr2, max, mult;
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ehci->periodic_sched_active = PERIODIC_ACTIVE;
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@@ -1479,9 +1479,10 @@ static int ehci_process_itd(EHCIState *ehci,
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ehci_raise_irq(ehci, USBSTS_INT);
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}
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itd->transact[i] &= ~ITD_XACT_ACTIVE;
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+ xfers++;
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}
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}
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- return 0;
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+ return xfers ? 0 : -1;
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}
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