Commit "156a2e4 ehci: make idt processing more robust" tries to avoid a
DoS by the guest (create a circular iTD queue and let qemu ehci
emulation run in circles forever). Unfortunately this has two problems:
First it misses the case of siTDs, and second it reportedly breaks
FreeBSD.
So lets go for a different approach: just count the number of iTDs and
siTDs we have seen per frame and apply a limit. That should really
catch all cases now.
Reported-by: 杜少博 <dusha...@360.cn>
Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
---
hw/usb/hcd-ehci.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 159f58d..d5c0e1c 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -2011,6 +2011,7 @@ static int ehci_state_writeback(EHCIQueue *q)
static void ehci_advance_state(EHCIState *ehci, int async)
{
EHCIQueue *q = NULL;
+ int itd_count = 0;
int again;
do {
@@ -2035,10 +2036,12 @@ static void ehci_advance_state(EHCIState *ehci, int
async)
case EST_FETCHITD:
again = ehci_state_fetchitd(ehci, async);
+ itd_count++;
break;
case EST_FETCHSITD:
again = ehci_state_fetchsitd(ehci, async);
+ itd_count++;
break;
case EST_ADVANCEQUEUE:
@@ -2087,7 +2090,8 @@ static void ehci_advance_state(EHCIState *ehci, int async)
break;
}
- if (again < 0) {
+ if (again < 0 || itd_count > 16) {
+ /* TODO: notify guest (raise HSE irq?) */
fprintf(stderr, "processing error - resetting ehci HC\n");
ehci_reset(ehci);
again = 0;
--
1.8.3.1
