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hw/usb/hcd-dwc2: fix divide-by-zero in dwc2_handle_packet()

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Check the value of mps to avoid potential divide-by-zero later in the function.
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>
Reviewed-by: Paul Zimmerman <pauldzim@gmail.com>
Reported-by: Gaoning Pan <gaoning.pgn@antgroup.com>
Reported-by: Xingwei Lin <linyi.lxw@antfin.com>
Message-id: 20201015075957.268823-1-mcascell@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Mauro Matteo Cascella 2020-10-15 09:59:57 +02:00 committed by Gerd Hoffmann
parent ccee80c68d
commit bea2a9e3e0
1 changed files with 6 additions and 0 deletions
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6
hw/usb/hcd-dwc2.c
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@ -250,6 +250,12 @@ static void dwc2_handle_packet(DWC2State *s, uint32_t devadr, USBDevice *dev,
trace_usb_dwc2_handle_packet(chan, dev, &p->packet, epnum, types[eptype],
dirs[epdir], mps, len, pcnt);
if (mps == 0) {
qemu_log_mask(LOG_GUEST_ERROR,
"%s: Bad HCCHAR_MPS set to zero\n", __func__);
return;
}
if (eptype == USB_ENDPOINT_XFER_CONTROL && pid == TSIZ_SC_MC_PID_SETUP) {
pid = USB_TOKEN_SETUP;
} else {