Commit 53e5f36f authored Aug 23, 2016 by Alan Stern Committed by Greg Kroah-Hartman Aug 23, 2016

USB: avoid left shift by -1



UBSAN complains about a left shift by -1 in proc_do_submiturb().  This
can occur when an URB is submitted for a bulk or control endpoint on
a high-speed device, since the code doesn't bother to check the
endpoint type; normally only interrupt or isochronous endpoints have
a nonzero bInterval value.

Aside from the fact that the operation is illegal, it shouldn't matter
because the result isn't used.  Still, in theory it could cause a
hardware exception or other problem, so we should work around it.
This patch avoids doing the left shift unless the shift amount is >= 0.

The same piece of code has another problem.  When checking the device
speed (the exponential encoding for interrupt endpoints is used only
by high-speed or faster devices), we need to look for speed >=
USB_SPEED_SUPER as well as speed == USB_SPEED HIGH.  The patch adds
this check.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Vittorio Zecca <zeccav@gmail.com>
Tested-by: Vittorio Zecca <zeccav@gmail.com>
Suggested-by: Bjørn Mork <bjorn@mork.no>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 6c73358c

drivers/usb/core/devio.c

+11 −5

Original line number	Diff line number	Diff line
		@@ -1709,11 +1709,17 @@ static int proc_do_submiturb(struct usb_dev_state ps, struct usbdevfs_urb uurb
		as->urb->start_frame = uurb->start_frame;
		as->urb->number_of_packets = number_of_packets;
		as->urb->stream_id = stream_id;

		if (ep->desc.bInterval) {
		if (uurb->type == USBDEVFS_URB_TYPE_ISO \|\|
		ps->dev->speed == USB_SPEED_HIGH)
		as->urb->interval = 1 << min(15, ep->desc.bInterval - 1);
		ps->dev->speed == USB_SPEED_HIGH \|\|
		ps->dev->speed >= USB_SPEED_SUPER)
		as->urb->interval = 1 <<
		min(15, ep->desc.bInterval - 1);
		else
		as->urb->interval = ep->desc.bInterval;
		}

		as->urb->context = as;
		as->urb->complete = async_completed;
		for (totlen = u = 0; u < number_of_packets; u++) {

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