[PATCH 5.14 074/169] can: j1939: j1939_xtp_rx_rts_session_new(): abort TP less than 9 bytes

Greg Kroah-Hartman
2021-10-25T19:49:38Z

From: Zhang Changzhong <zhangchangzhong@huawei.com>

commit a4fbe70c5cb746441d56b28cf88161d9e0e25378 upstream.

The receiver should abort TP if 'total message size' in TP.CM_RTS and
TP.CM_BAM is less than 9 or greater than 1785 [1], but currently the
j1939 stack only checks the upper bound and the receiver will accept
the following broadcast message:

vcan1 18ECFF00 [8] 20 08 00 02 FF 00 23 01
vcan1 18EBFF00 [8] 01 00 00 00 00 00 00 00
vcan1 18EBFF00 [8] 02 00 FF FF FF FF FF FF

This patch adds check for the lower bound and abort illegal TP.

[1] SAE-J1939-82 A.3.4 Row 2 and A.3.6 Row 6.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Link: https://lore.kernel.org/all/1634203601-3460-1-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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/can/j1939/j1939-priv.h | 1 +
net/can/j1939/transport.c | 2 ++
2 files changed, 3 insertions(+)

--- a/net/can/j1939/j1939-priv.h
+++ b/net/can/j1939/j1939-priv.h
@@ -326,6 +326,7 @@ int j1939_session_activate(struct j1939_
void j1939_tp_schedule_txtimer(struct j1939_session *session, int msec);
void j1939_session_timers_cancel(struct j1939_session *session);

+#define J1939_MIN_TP_PACKET_SIZE 9
#define J1939_MAX_TP_PACKET_SIZE (7 * 0xff)
#define J1939_MAX_ETP_PACKET_SIZE (7 * 0x00ffffff)

--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -1596,6 +1596,8 @@ j1939_session *j1939_xtp_rx_rts_session_
abort = J1939_XTP_ABORT_FAULT;
else if (len > priv->tp_max_packet_size)
abort = J1939_XTP_ABORT_RESOURCE;
+ else if (len < J1939_MIN_TP_PACKET_SIZE)
+ abort = J1939_XTP_ABORT_FAULT;
}

if (abort != J1939_XTP_NO_ABORT) {