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From 20009bdaf95d10bf748fa69b104672d3cfaceddf Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Fri, 7 Oct 2016 10:15:29 +0200
Subject: [PATCH] xhci: limit the number of link trbs we are willing to process
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
hw/usb/hcd-xhci.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 726435c..ee4fa48 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -54,6 +54,8 @@
* to the specs when it gets them */
#define ER_FULL_HACK
+#define TRB_LINK_LIMIT 4
+
#define LEN_CAP 0x40
#define LEN_OPER (0x400 + 0x10 * MAXPORTS)
#define LEN_RUNTIME ((MAXINTRS + 1) * 0x20)
@@ -1000,6 +1002,7 @@ static TRBType xhci_ring_fetch(XHCIState *xhci, XHCIRing *ring, XHCITRB *trb,
dma_addr_t *addr)
{
PCIDevice *pci_dev = PCI_DEVICE(xhci);
+ uint32_t link_cnt = 0;
while (1) {
TRBType type;
@@ -1026,6 +1029,9 @@ static TRBType xhci_ring_fetch(XHCIState *xhci, XHCIRing *ring, XHCITRB *trb,
ring->dequeue += TRB_SIZE;
return type;
} else {
+ if (++link_cnt > TRB_LINK_LIMIT) {
+ return 0;
+ }
ring->dequeue = xhci_mask64(trb->parameter);
if (trb->control & TRB_LK_TC) {
ring->ccs = !ring->ccs;
@@ -1043,6 +1049,7 @@ static int xhci_ring_chain_length(XHCIState *xhci, const XHCIRing *ring)
bool ccs = ring->ccs;
/* hack to bundle together the two/three TDs that make a setup transfer */
bool control_td_set = 0;
+ uint32_t link_cnt = 0;
while (1) {
TRBType type;
@@ -1058,6 +1065,9 @@ static int xhci_ring_chain_length(XHCIState *xhci, const XHCIRing *ring)
type = TRB_TYPE(trb);
if (type == TR_LINK) {
+ if (++link_cnt > TRB_LINK_LIMIT) {
+ return -length;
+ }
dequeue = xhci_mask64(trb.parameter);
if (trb.control & TRB_LK_TC) {
ccs = !ccs;
--
1.8.3.1
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