Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Zhang Changzhong <zhangchangzhong@huawei.com>
To:     Robin van der Gracht <robin@protonic.nl>,
        Oleksij Rempel <linux@rempel-privat.de>,
        <kernel@pengutronix.de>, Oliver Hartkopp <socketcan@hartkopp.net>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>
CC:     Zhang Changzhong <zhangchangzhong@huawei.com>,
        <linux-can@vger.kernel.org>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: [PATCH net 3/3] can: j1939: j1939_tp_cmd_recv(): check the dst address of TP.CM_BAM
Date:   Thu, 21 Oct 2021 22:04:17 +0800
Message-ID: <1634825057-47915-4-git-send-email-zhangchangzhong@huawei.com>
In-Reply-To: <1634825057-47915-1-git-send-email-zhangchangzhong@huawei.com>
References: <1634825057-47915-1-git-send-email-zhangchangzhong@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

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 tranport:
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")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
---
 net/can/j1939/transport.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 2efa606..93ec0c3 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -2019,6 +2019,8 @@ static void j1939_tp_cmd_recv(struct j1939_priv *priv, struct sk_buff *skb)
 		extd = J1939_ETP;
 		fallthrough;
 	case J1939_TP_CMD_BAM:
+		if (!j1939_cb_is_broadcast(skcb))
+			return;
 		fallthrough;
 	case J1939_TP_CMD_RTS:
 		if (skcb->addr.type != extd)
-- 
2.9.5