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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Jimmy Assarsson" <jimmyassarsson@gmail.com>,
        "Marc Kleine-Budde" <mkl@pengutronix.de>
Date:   Wed, 28 Feb 2018 15:20:18 +0000
Message-ID: <lsq.1519831218.861434654@decadent.org.uk>
Subject: [PATCH 3.16 042/254] can: kvaser_usb: Fix comparison bug in
 kvaser_usb_read_bulk_callback()
In-Reply-To: <lsq.1519831217.271785318@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jimmy Assarsson <jimmyassarsson@gmail.com>

commit e84f44eb5523401faeb9cc1c97895b68e3cfb78d upstream.

The conditon in the while-loop becomes true when actual_length is less than
2 (MSG_HEADER_LEN). In best case we end up with a former, already
dispatched msg, that got msg->len greater than actual_length. This will
result in a "Format error" error printout.

Problem seen when unplugging a Kvaser USB device connected to a vbox guest.

warning: comparison between signed and unsigned integer expressions
[-Wsign-compare]

Signed-off-by: Jimmy Assarsson <jimmyassarsson@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/net/can/usb/kvaser_usb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -983,7 +983,7 @@ static void kvaser_usb_read_bulk_callbac
 		goto resubmit_urb;
 	}
 
-	while (pos <= urb->actual_length - MSG_HEADER_LEN) {
+	while (pos <= (int)(urb->actual_length - MSG_HEADER_LEN)) {
 		msg = urb->transfer_buffer + pos;
 
 		/* The Kvaser firmware can only read and write messages that