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[Qemu-devel] [PATCH] usb: ohci: limit the number of link eds
From: |
Li Qiang |
Subject: |
[Qemu-devel] [PATCH] usb: ohci: limit the number of link eds |
Date: |
Tue, 7 Feb 2017 02:23:33 -0800 |
From: Li Qiang <address@hidden>
The guest may builds an infinite loop with link eds. This patch
limit the number of linked ed to avoid this.
Signed-off-by: Li Qiang <address@hidden>
---
hw/usb/hcd-ohci.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
index c82a92f..4a63f3b 100644
--- a/hw/usb/hcd-ohci.c
+++ b/hw/usb/hcd-ohci.c
@@ -42,6 +42,8 @@
#define OHCI_MAX_PORTS 15
+#define ED_LINK_LIMIT 4
+
static int64_t usb_frame_time;
static int64_t usb_bit_time;
@@ -1184,7 +1186,7 @@ static int ohci_service_ed_list(OHCIState *ohci, uint32_t
head, int completion)
uint32_t next_ed;
uint32_t cur;
int active;
-
+ uint32_t link_cnt = 0;
active = 0;
if (head == 0)
@@ -1199,6 +1201,11 @@ static int ohci_service_ed_list(OHCIState *ohci,
uint32_t head, int completion)
next_ed = ed.next & OHCI_DPTR_MASK;
+ if (++link_cnt > ED_LINK_LIMIT) {
+ ohci_die(ohci);
+ return 0;
+ }
+
if ((ed.head & OHCI_ED_H) || (ed.flags & OHCI_ED_K)) {
uint32_t addr;
/* Cancel pending packets for ED that have been paused. */
--
1.8.3.1
- [Qemu-devel] [PATCH] usb: ohci: limit the number of link eds,
Li Qiang <=