From 30ffd5332e06316bd69a654c06aa033872979b7c Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp <socketcan@hartkopp.net>
Date: Wed, 16 Mar 2022 17:42:57 +0100
Subject: [PATCH] can: isotp: return -EADDRNOTAVAIL when reading from unbound socket
Git-commit: 30ffd5332e06316bd69a654c06aa033872979b7c
Patch-mainline: v5.18-rc1
References: git-fixes

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
Link: https://lore.kernel.org/all/20220316164258.54155-2-socketcan@hartkopp.net
Suggested-by: Derek Will <derekrobertwill@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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
@@ -1046,12 +1046,16 @@ static int isotp_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 {
 	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;
-- 
2.31.1