[PATCH v2 13/17] can: bittiming: can_sjw_check(): check that SJW is not longer than either Phase Buffer Segment

[Marc Kleine-Budde <mkl@pengutronix.de>]

According to "The Configuration of the CAN Bit Timing" [1] the SJW
"may not be longer than either Phase Buffer Segment".

Check SJW against length of both Phase buffers. In case the SJW is
greater, report an error via netlink to user space and bail out.

[1] http://web.archive.org/http://www.oertel-halle.de/files/cia99paper.pdf

Suggested-by: Vincent Mailhol <vincent.mailhol@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/dev/bittiming.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/net/can/dev/bittiming.c b/drivers/net/can/dev/bittiming.c
index 0a2a9b12565f..68287b79afe8 100644
--- a/drivers/net/can/dev/bittiming.c
+++ b/drivers/net/can/dev/bittiming.c
@@ -24,6 +24,20 @@ int can_sjw_check(const struct net_device *dev, const struct can_bittiming *bt,
 		return -EINVAL;
 	}
 
+	if (bt->sjw > bt->phase_seg1) {
+		NL_SET_ERR_MSG_FMT(extack,
+				   "sjw: %u greater than phase-seg1: %u",
+				   bt->sjw, bt->phase_seg1);
+		return -EINVAL;
+	}
+
+	if (bt->sjw > bt->phase_seg2) {
+		NL_SET_ERR_MSG_FMT(extack,
+				   "sjw: %u greater than phase-seg2: %u",
+				   bt->sjw, bt->phase_seg2);
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
-- 
2.39.1