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From: Li Qiang <liqiang6-s@360.cn>
Date: Tue, 7 Feb 2017 10:23:33 +0000 (-0800)
Subject: usb: ohci: limit the number of link eds
X-Git-Tag: v2.9.0-rc0~85^2~8
X-Git-Url: http://git.qemu.org/?p=qemu.git;a=commitdiff_plain;h=95ed56939eb2eaa4e2f349fe6dcd13ca4edfd8fb
usb: ohci: limit the number of link eds
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 <liqiang6-s@360.cn>
Message-id: 5899a02e.45ca240a.6c373.93c1@mx.google.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
index 2cba3e3..21c93e0 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. */
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