netdev - [PATCH v1] j1939: transport: make sure EOMA is send with the total message size set

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Message-Id: <20191025093015.24506-1-o.rempel@pengutronix.de>
Date:   Fri, 25 Oct 2019 11:30:15 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     dev.kurt@...dijck-laurijssen.be, mkl@...gutronix.de,
        wg@...ndegger.com
Cc:     Oleksij Rempel <o.rempel@...gutronix.de>, kernel@...gutronix.de,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v1] j1939: transport: make sure EOMA is send with the total message size set

We was sending malformed EOMA with total message size set to 0. So, fix this
bug and add sanity check to the RX path.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 net/can/j1939/transport.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index fe000ea757ea..a82097427642 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -1273,9 +1273,27 @@ j1939_xtp_rx_abort(struct j1939_priv *priv, struct sk_buff *skb,
 static void
 j1939_xtp_rx_eoma_one(struct j1939_session *session, struct sk_buff *skb)
 {
+	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+	const u8 *dat;
+	int len;
+
 	if (j1939_xtp_rx_cmd_bad_pgn(session, skb))
 		return;
 
+	dat = skb->data;
+
+	if (skcb->addr.type == J1939_ETP)
+		len = j1939_etp_ctl_to_size(dat);
+	else
+		len = j1939_tp_ctl_to_size(dat);
+
+	if (session->total_message_size != len) {
+		netdev_warn(session->priv->ndev, "%s: 0x%p: Incorrect size. Expected: %i; got: %i.\n",
+			    __func__, session, session->total_message_size,
+			    len);
+		return;
+	}
+
 	netdev_dbg(session->priv->ndev, "%s: 0x%p\n", __func__, session);
 
 	session->pkt.tx_acked = session->pkt.total;
@@ -1432,7 +1450,7 @@ j1939_session *j1939_session_fresh_new(struct j1939_priv *priv,
 	skcb = j1939_skb_to_cb(skb);
 	memcpy(skcb, rel_skcb, sizeof(*skcb));
 
-	session = j1939_session_new(priv, skb, skb->len);
+	session = j1939_session_new(priv, skb, size);
 	if (!session) {
 		kfree_skb(skb);
 		return NULL;
-- 
2.23.0