can: isotp: fix msg_namelen values depending on CAN_REQUIRED_SIZE

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>

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 15ea1234d45730232941a1bbbe441466f865af46..9f94ad3caee92938a81e0fb22e850ec97d73b9c9 100644 (file)
--- 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,