[PATCH v1] can: j1939: j1939_tp_cmd_recv(): check the dst address of TP.CM_BAM

* [PATCH v1] can: j1939: j1939_tp_cmd_recv(): check the dst address of TP.CM_BAM
@ 2021-12-01 10:25 Oleksij Rempel
  2021-12-02 15:35 ` Greg KH
  0 siblings, 1 reply; 3+ messages in thread
From: Oleksij Rempel @ 2021-12-01 10:25 UTC (permalink / raw)
  To: stable; +Cc: Zhang Changzhong, Oleksij Rempel, Marc Kleine-Budde

From: Zhang Changzhong <zhangchangzhong@huawei.com>

commit 164051a6ab5445bd97f719f50b16db8b32174269 upstream.

The TP.CM_BAM message must be sent to the global address [1], so add a
check to drop TP.CM_BAM sent to a non-global address.

Without this patch, the receiver will treat the following packets as
normal RTS/CTS transport:
18EC0102#20090002FF002301
18EB0102#0100000000000000
18EB0102#020000FFFFFFFFFF

[1] SAE-J1939-82 2015 A.3.3 Row 1.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Link: https://lore.kernel.org/all/1635431907-15617-4-git-send-email-zhangchangzhong@huawei.com
Cc: stable@vger.kernel.org
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
changes:
 - rebase against v5.10.82

 net/can/j1939/transport.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index fe35fdad35c9..9c39b0f5d6e0 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -2004,6 +2004,12 @@ static void j1939_tp_cmd_recv(struct j1939_priv *priv, struct sk_buff *skb)
 		extd = J1939_ETP;
 		fallthrough;
 	case J1939_TP_CMD_BAM:
+		if (cmd == J1939_TP_CMD_BAM && !j1939_cb_is_broadcast(skcb)) {
+			netdev_err_once(priv->ndev, "%s: BAM to unicast (%02x), ignoring!\n",
+					__func__, skcb->addr.sa);
+			return;
+		}
+		fallthrough;
 	case J1939_TP_CMD_RTS: /* fall through */
 		if (skcb->addr.type != extd)
 			return;
-- 
2.30.2


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