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

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Message-Id: <20201105112427.40688-1-colin.king@canonical.com>
Date:   Thu,  5 Nov 2020 11:24:27 +0000
From:   Colin King <colin.king@...onical.com>
To:     Wolfgang Grandegger <wg@...ndegger.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Stephane Grosjean <s.grosjean@...k-system.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] can: usb: fix potential integer overflow on shift of a int

From: Colin Ian King <colin.king@...onical.com>

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 <colin.king@...onical.com>
---
 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