[PATCH 2/3] can: isotp: return -EADDRNOTAVAIL when reading from unbound socket

[Oliver Hartkopp <socketcan@hartkopp.net>]

When reading from an unbound can-isotp socket the syscall blocked
indefinitely. As unbound sockets (without given CAN address information)
do not make sense anyway we directly return -EADDRNOTAVAIL on read()
analogue to the known behavior from sendmsg().

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Link: https://github.com/linux-can/can-utils/issues/349
Suggested-by: Derek Will <derekrobertwill@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/isotp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 1662103ce125..6b6c82206c30 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1044,16 +1044,20 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 			 int flags)
 {
 	struct sock *sk = sock->sk;
 	struct sk_buff *skb;
+	struct isotp_sock *so = isotp_sk(sk);
 	int err = 0;
 	int noblock;
 
 	noblock = flags & MSG_DONTWAIT;
 	flags &= ~MSG_DONTWAIT;
 
+	if (!so->bound)
+		return -EADDRNOTAVAIL;
+
 	skb = skb_recv_datagram(sk, flags, noblock, &err);
 	if (!skb)
 		return err;
 
 	if (size < skb->len)
-- 
2.30.2