[PATCH 3.16 069/136] usb: udc: lpc32xx: fix bad bit shift operation

Ben Hutchings
2019-12-17T00:56:21Z

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>

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: 24a28e428351 ("USB: gadget driver for LPC32xx")
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>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/gadget/lpc32xx_udc.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/usb/gadget/lpc32xx_udc.c
+++ b/drivers/usb/gadget/lpc32xx_udc.c
@@ -1228,11 +1228,11 @@ static void udc_pop_fifo(struct lpc32xx_
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;