USB: fix out-of-bounds in usb_set_configuration

USB: fix out-of-bounds in usb_set_configuration

commit bd7a3fe770ebd8391d1c7d072ff88e9e76d063eb upstream.

Andrey Konovalov reported a possible out-of-bounds problem for a USB interface
association descriptor.  He writes:
	It seems there's no proper size check of a USB_DT_INTERFACE_ASSOCIATION
	descriptor. It's only checked that the size is >= 2 in
	usb_parse_configuration(), so find_iad() might do out-of-bounds access
	to intf_assoc->bInterfaceCount.

And he's right, we don't check for crazy descriptors of this type very well, so
resolve this problem.  Yet another issue found by syzkaller...

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[sw0312.kim: cherry-pick from linux-3.16.y to fix CVE-2017-16531]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I2413801c6cf5e9eeda0280ba859466d01f5fd9d9