From 95ed56939eb2eaa4e2f349fe6dcd13ca4edfd8fb Mon Sep 17 00:00:00 2001 From: Li Qiang Date: Tue, 7 Feb 2017 02:23:33 -0800 Subject: [PATCH] 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 Message-id: 5899a02e.45ca240a.6c373.93c1@mx.google.com Signed-off-by: Gerd Hoffmann --- 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 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. */ -- 2.10.2