USB: avoid left shift by -1
authorAlan Stern <stern@rowland.harvard.edu>
Tue, 23 Aug 2016 19:32:51 +0000 (15:32 -0400)
committerBen Hutchings <ben@decadent.org.uk>
Sun, 20 Nov 2016 01:01:34 +0000 (01:01 +0000)
commitc1251c319e8790b9827be7786db8c0e59f9a2c37
tree9ecb3e519eacae773bcce9a61970997b10bf692f
parent285f39c806ac8d374c93b9c46f286804b2a4f9e9
USB: avoid left shift by -1

commit 53e5f36fbd2453ad69a3369a1db62dc06c30a4aa upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
drivers/usb/core/devio.c