usb: udc: lpc32xx: fix bad bit shift operation

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: 24a28e428351 ("USB: gadget driver for LPC32xx")
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20191014191830.GA10721@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
index 2b1f3cc7819bfb0b49a118a545486efaec024c2c..bf6c81e2f8cccf9e2d6644d728141e7991749de9 100644 (file)
--- a/drivers/usb/gadget/udc/lpc32xx_udc.c
+++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
@@ -1177,11 +1177,11 @@ 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;