[PATCH][next] can: usb: fix potential integer overflow on shift of a int

From: Colin Ian King <redacted>

The left shift of int 32 bit integer constant 1 is evaluated using
32 bit arithmetic and then assigned to a signed 64 bit variable. In
the case where time_ref->adapter->ts_used_bits is 32 or more this
can lead to an oveflow. Avoid this by shifting using the BIT_ULL macro
instead.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: bb4785551f64 ("can: usb: PEAK-System Technik USB adapters driver core")
Signed-off-by: Colin Ian King <redacted>
---
 drivers/net/can/usb/peak_usb/pcan_usb_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_core.c b/drivers/net/can/usb/peak_usb/pcan_usb_core.c
index c2764799f9ef..204ccb27d6d9 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb_core.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_core.c

@@ -156,7 +156,7 @@ void peak_usb_get_ts_time(struct peak_time_ref *time_ref, u32 ts, ktime_t *time)
 		if (time_ref->ts_dev_1 < time_ref->ts_dev_2) {
 			/* case when event time (tsw) wraps */
 			if (ts < time_ref->ts_dev_1)
-				delta_ts = 1 << time_ref->adapter->ts_used_bits;
+				delta_ts = BIT_ULL(time_ref->adapter->ts_used_bits);
 
 		/* Otherwise, sync time counter (ts_dev_2) has wrapped:
 		 * handle case when event time (tsn) hasn't.

@@ -168,7 +168,7 @@ void peak_usb_get_ts_time(struct peak_time_ref *time_ref, u32 ts, ktime_t *time)
 		 *              tsn            ts
 		 */
 		} else if (time_ref->ts_dev_1 < ts) {
-			delta_ts = -(1 << time_ref->adapter->ts_used_bits);
+			delta_ts = -BIT_ULL(time_ref->adapter->ts_used_bits);
 		}
 
 		/* add delay between last sync and event timestamps */

-- 
2.27.0

On 11/5/20 12:24 PM, Colin King wrote:

From: Colin Ian King <redacted>

The left shift of int 32 bit integer constant 1 is evaluated using
32 bit arithmetic and then assigned to a signed 64 bit variable. In
the case where time_ref->adapter->ts_used_bits is 32 or more this
can lead to an oveflow. Avoid this by shifting using the BIT_ULL macro
instead.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: bb4785551f64 ("can: usb: PEAK-System Technik USB adapters driver core")
Signed-off-by: Colin Ian King <redacted>

Applied to linux-can/testing (not to next).

Thanks,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |