[PATCH 5.11 127/210] can: isotp: fix msg_namelen values depending on CAN_REQUIRED_SIZE

Greg Kroah-Hartman
2021-04-12T09:34:08Z

From: Oliver Hartkopp <socketcan@hartkopp.net>

[ Upstream commit f522d9559b07854c231cf8f0b8cb5a3578f8b44e ]

Since commit f5223e9eee65 ("can: extend sockaddr_can to include j1939
members") the sockaddr_can has been extended in size and a new
CAN_REQUIRED_SIZE macro has been introduced to calculate the protocol
specific needed size.

The ABI for the msg_name and msg_namelen has not been adapted to the
new CAN_REQUIRED_SIZE macro for the other CAN protocols which leads to
a problem when an existing binary reads the (increased) struct
sockaddr_can in msg_name.

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Reported-by: Richard Weinberger <richard@nod.at>
Acked-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Link: https://lore.kernel.org/linux-can/1135648123.112255.1616613706554.JavaMail.zimbra@nod.at/T/#t
Link: https://lore.kernel.org/r/20210325125850.1620-2-socketcan@hartkopp.net
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/can/isotp.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 15ea1234d457..9f94ad3caee9 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -77,6 +77,8 @@ MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
MODULE_ALIAS("can-proto-6");

+#define ISOTP_MIN_NAMELEN CAN_REQUIRED_SIZE(struct sockaddr_can, can_addr.tp)
+
#define SINGLE_MASK(id) (((id) & CAN_EFF_FLAG) ? \
(CAN_EFF_MASK | CAN_EFF_FLAG | CAN_RTR_FLAG) : \
(CAN_SFF_MASK | CAN_EFF_FLAG | CAN_RTR_FLAG))
@@ -986,7 +988,8 @@ static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
sock_recv_timestamp(msg, sk, skb);

if (msg->msg_name) {
- msg->msg_namelen = sizeof(struct sockaddr_can);
+ __sockaddr_check_size(ISOTP_MIN_NAMELEN);
+ msg->msg_namelen = ISOTP_MIN_NAMELEN;
memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
}

@@ -1056,7 +1059,7 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
int notify_enetdown = 0;
int do_rx_reg = 1;

- if (len < CAN_REQUIRED_SIZE(struct sockaddr_can, can_addr.tp))
+ if (len < ISOTP_MIN_NAMELEN)
return -EINVAL;

/* do not register frame reception for functional addressing */
@@ -1152,13 +1155,13 @@ static int isotp_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
if (peer)
return -EOPNOTSUPP;

- memset(addr, 0, sizeof(*addr));
+ memset(addr, 0, ISOTP_MIN_NAMELEN);
addr->can_family = AF_CAN;
addr->can_ifindex = so->ifindex;
addr->can_addr.tp.rx_id = so->rxid;
addr->can_addr.tp.tx_id = so->txid;

- return sizeof(*addr);
+ return ISOTP_MIN_NAMELEN;
}

static int isotp_setsockopt(struct socket *sock, int level, int optname,
--
2.30.2