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Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet()
From: |
Paul Zimmerman |
Subject: |
Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet() |
Date: |
Mon, 12 Oct 2020 13:34:14 -0700 |
On Mon, Oct 12, 2020 at 8:05 AM Mauro Matteo Cascella
<mcascell@redhat.com> wrote:
>
> Check the value of mps before it is used as divisor. Since HCCHAR_MPS is guest
> controllable, this prevents a malicious/buggy guest from crashing the QEMU
> process on the host.
>
> Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
> Reported-by: Gaoning Pan <gaoning.pgn@antgroup.com>
> Reported-by: Xingwei Lin <linyi.lxw@antfin.com>
> ---
> hw/usb/hcd-dwc2.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/hw/usb/hcd-dwc2.c b/hw/usb/hcd-dwc2.c
> index 97688d21bf..91476fd781 100644
> --- a/hw/usb/hcd-dwc2.c
> +++ b/hw/usb/hcd-dwc2.c
> @@ -324,6 +324,12 @@ babble:
> }
> }
>
> + if (mps == 0) {
> + qemu_log_mask(LOG_GUEST_ERROR,
> + "%s: Bad HCCHAR_MPS set to zero\n", __func__);
> + return;
> + }
> +
> tpcnt = actual / mps;
> if (actual % mps) {
> tpcnt++;
> --
> 2.26.2
>
Hi Mauro,
I think it would be better to move this check earlier in the function,
just after 'mps' is read from the register. Otherwise it can get
assigned to 'tlen' and 'p->mps', and who knows what mischief an
invalid value there might cause.
After that, you can add my
Reviewed-by: Paul Zimmerman <pauldzim@gmail.com>
Thanks,
Paul
- [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(), Mauro Matteo Cascella, 2020/10/12
- Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(),
Paul Zimmerman <=
- Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(), Gerd Hoffmann, 2020/10/13
- Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(), Paul Zimmerman, 2020/10/13
- Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(), Gerd Hoffmann, 2020/10/13
- Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(), Mauro Matteo Cascella, 2020/10/14
- Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(), Paul Zimmerman, 2020/10/15
- Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(), Gerd Hoffmann, 2020/10/15
- Re: [PATCH] hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet(), Gerd Hoffmann, 2020/10/14