HID: hid-cypress: validate length of report

HID: hid-cypress: validate length of report

Make sure we have enough of a report structure to validate before
looking at it.

Orabug: 25795985
CVE: CVE-2017-7273

Reported-by: Benoit Camredon <benoit.camredon@airbus.com>
Tested-by: Benoit Camredon <benoit.camredon@airbus.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
(cherry picked from commit 1ebb71143758f45dc0fa76e2f48429e13b16d110)
Signed-off-by: Aniket Alshi <aniket.alshi@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>