Hello Gerd,
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2017-02-07 18:23 GMT+08:00 Li Qiang <liq3ea@gmail.com>:
> From: Li Qiang <liqiang6-s@360.cn>
>
> 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>
> ---
> 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
>
>