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xhci: limit the number of link trbs we are willing to process

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Needed to avoid we run in circles forever in case the guest builds
an endless loop with link trbs.

Reported-by: Li Qiang <liqiang6-s@360.cn>
Tested-by: P J P <ppandit@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1476096382-7981-1-git-send-email-kraxel@redhat.com
This commit is contained in:
Gerd Hoffmann 2016-10-10 12:46:22 +02:00
parent 6b39b06339
commit 05f43d44e4
1 changed files with 10 additions and 0 deletions
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10
hw/usb/hcd-xhci.c
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@ -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;