[PATCH 1/1] usb: usbip: vudc: fix left shift overflow

From: Nicolas Iooss
Date: Tue Aug 23 2016 - 11:15:36 EST


In v_recv_cmd_submit(), urb_p->urb->pipe has the type unsigned int
(which is 32-bit long on x86_64) but 11<<30 results in a 34-bit integer.
Therefore the 2 leading bits are truncated and

urb_p->urb->pipe &= ~(11 << 30);

has the same meaning as

urb_p->urb->pipe &= ~(3 << 30);

This second statement seems to be how the code was intended to be
written, as PIPE_ constants have values between 0 and 3.

The overflow has been detected with a clang warning:

drivers/usb/usbip/vudc_rx.c:145:27: warning: signed shift result
(0x2C0000000) requires 35 bits to represent, but 'int' only has 32
bits [-Wshift-overflow]
urb_p->urb->pipe &= ~(11 << 30);
~~ ^ ~~

Fixes: 79c02cb1fd5c ("usbip: vudc: Add vudc_rx")
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
---
drivers/usb/usbip/vudc_rx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/usbip/vudc_rx.c b/drivers/usb/usbip/vudc_rx.c
index 344bd9473475..e429b59f6f8a 100644
--- a/drivers/usb/usbip/vudc_rx.c
+++ b/drivers/usb/usbip/vudc_rx.c
@@ -142,7 +142,7 @@ static int v_recv_cmd_submit(struct vudc *udc,
urb_p->urb->status = -EINPROGRESS;

/* FIXME: more pipe setup to please usbip_common */
- urb_p->urb->pipe &= ~(11 << 30);
+ urb_p->urb->pipe &= ~(3 << 30);
switch (urb_p->ep->type) {
case USB_ENDPOINT_XFER_BULK:
urb_p->urb->pipe |= (PIPE_BULK << 30);
--
2.9.3