diff options
| author | Gerd Hoffmann <kraxel@redhat.com> | 2016-04-18 09:11:38 +0200 |
|---|---|---|
| committer | Gerd Hoffmann <kraxel@redhat.com> | 2016-04-19 08:18:27 +0200 |
| commit | 1ae3f2f178087711f9591350abad133525ba93f2 (patch) | |
| tree | 3823cf7dd8d30c31a7c154d067801a73cc53bcfd | |
| parent | c6c598ca5fba68fbd6612f3330c4015142f2f86a (diff) | |
ehci: apply limit to iTD/sidt descriptors
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 <dushaobo@360.cn>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
| -rw-r--r-- | hw/usb/hcd-ehci.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c index 159f58d5a0..d5c0e1c60d 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; |