60 lines
2.0 KiB
Diff
60 lines
2.0 KiB
Diff
From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Mon, 18 Apr 2016 09:11:38 +0200
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Subject: [PATCH] ehci: apply limit to iTD/sidt descriptors
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Commit "156a2e4 ehci: make idt processing more robust" tries to avoid a
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DoS by the guest (create a circular iTD queue and let qemu ehci
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emulation run in circles forever). Unfortunately this has two problems:
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First it misses the case of siTDs, and second it reportedly breaks
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FreeBSD.
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So lets go for a different approach: just count the number of iTDs and
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siTDs we have seen per frame and apply a limit. That should really
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catch all cases now.
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Reported-by: 杜少博 <dushaobo@360.cn>
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit 1ae3f2f178087711f9591350abad133525ba93f2)
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---
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hw/usb/hcd-ehci.c | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
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index d6d7de3..8dbfbe3 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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@@ -2003,6 +2003,7 @@ static int ehci_state_writeback(EHCIQueue *q)
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static void ehci_advance_state(EHCIState *ehci, int async)
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{
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EHCIQueue *q = NULL;
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+ int itd_count = 0;
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int again;
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do {
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@@ -2027,10 +2028,12 @@ static void ehci_advance_state(EHCIState *ehci, int async)
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case EST_FETCHITD:
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again = ehci_state_fetchitd(ehci, async);
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+ itd_count++;
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break;
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case EST_FETCHSITD:
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again = ehci_state_fetchsitd(ehci, async);
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+ itd_count++;
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break;
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case EST_ADVANCEQUEUE:
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@@ -2079,7 +2082,8 @@ static void ehci_advance_state(EHCIState *ehci, int async)
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break;
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}
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- if (again < 0) {
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+ if (again < 0 || itd_count > 16) {
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+ /* TODO: notify guest (raise HSE irq?) */
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fprintf(stderr, "processing error - resetting ehci HC\n");
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ehci_reset(ehci);
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again = 0;
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