usb: udc: lpc32xx: fix bad bit shift operation

commit b987b66ac3a2bc2f7b03a0ba48a07dc553100c07 upstream.

It seems that the right variable to use in this case is *i*, instead of
*n*, otherwise there is an undefined behavior when right shifiting by more
than 31 bits when multiplying n by 8; notice that *n* can take values
equal or greater than 4 (4, 8, 16, ...).

Also, notice that under the current conditions (bl = 3), we are skiping
the handling of bytes 3, 7, 31... So, fix this by updating this logic
and limit *bl* up to 4 instead of up to 3.

This fix is based on function udc_stuff_fifo().

Addresses-Coverity-ID: 1454834 ("Bad bit shift operation")
Fixes: 24a28e42 ("USB: gadget driver for LPC32xx")
Cc: stable@vger.kernel.org
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20191014191830.GA10721@embeddedorSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/lpc32xx_udc.c

@@ -1165,11 +1165,11 @@ static void udc_pop_fifo(struct lpc32xx_udc *udc, u8 *data, u32 bytes)
 			tmp = readl(USBD_RXDATA(udc->udp_baseaddr));
 
 			bl = bytes - n;
-			if (bl > 3)
-				bl = 3;
+			if (bl > 4)
+				bl = 4;
 
 			for (i = 0; i < bl; i++)
-				data[n + i] = (u8) ((tmp >> (n * 8)) & 0xFF);
+				data[n + i] = (u8) ((tmp >> (i * 8)) & 0xFF);
 		}
 		break;