Merge tag 'linux-can-fixes-for-5.13-20210512' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
pull-request: can 2021-05-12

this is a pull request of a single patch for net/master.

The patch is by Norbert Slusarek and it fixes a race condition in the
CAN ISO-TP socket between isotp_bind() and isotp_setsockopt().
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 33 insertions, 16 deletions

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 9f94ad3caee9..253b24417c8e 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -1062,27 +1062,31 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 	if (len < ISOTP_MIN_NAMELEN)
 		return -EINVAL;
 
+	if (addr->can_addr.tp.tx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG))
+		return -EADDRNOTAVAIL;
+
+	if (!addr->can_ifindex)
+		return -ENODEV;
+
+	lock_sock(sk);
+
 	/* do not register frame reception for functional addressing */
 	if (so->opt.flags & CAN_ISOTP_SF_BROADCAST)
 		do_rx_reg = 0;
 
 	/* do not validate rx address for functional addressing */
 	if (do_rx_reg) {
-		if (addr->can_addr.tp.rx_id == addr->can_addr.tp.tx_id)
-			return -EADDRNOTAVAIL;
+		if (addr->can_addr.tp.rx_id == addr->can_addr.tp.tx_id) {
+			err = -EADDRNOTAVAIL;
+			goto out;
+		}
 
-		if (addr->can_addr.tp.rx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG))
-			return -EADDRNOTAVAIL;
+		if (addr->can_addr.tp.rx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG)) {
+			err = -EADDRNOTAVAIL;
+			goto out;
+		}
 	}
 
-	if (addr->can_addr.tp.tx_id & (CAN_ERR_FLAG | CAN_RTR_FLAG))
-		return -EADDRNOTAVAIL;
-
-	if (!addr->can_ifindex)
-		return -ENODEV;
-
-	lock_sock(sk);
-
 	if (so->bound && addr->can_ifindex == so->ifindex &&
 	    addr->can_addr.tp.rx_id == so->rxid &&
 	    addr->can_addr.tp.tx_id == so->txid)
@@ -1164,16 +1168,13 @@ static int isotp_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
 	return ISOTP_MIN_NAMELEN;
 }
 
-static int isotp_setsockopt(struct socket *sock, int level, int optname,
+static int isotp_setsockopt_locked(struct socket *sock, int level, int optname,
 			    sockptr_t optval, unsigned int optlen)
 {
 	struct sock *sk = sock->sk;
 	struct isotp_sock *so = isotp_sk(sk);
 	int ret = 0;
 
-	if (level != SOL_CAN_ISOTP)
-		return -EINVAL;
-
 	if (so->bound)
 		return -EISCONN;
 
@@ -1248,6 +1249,22 @@ static int isotp_setsockopt(struct socket *sock, int level, int optname,
 	return ret;
 }
 
+static int isotp_setsockopt(struct socket *sock, int level, int optname,
+			    sockptr_t optval, unsigned int optlen)
+
+{
+	struct sock *sk = sock->sk;
+	int ret;
+
+	if (level != SOL_CAN_ISOTP)
+		return -EINVAL;
+
+	lock_sock(sk);
+	ret = isotp_setsockopt_locked(sock, level, optname, optval, optlen);
+	release_sock(sk);
+	return ret;
+}
+
 static int isotp_getsockopt(struct socket *sock, int level, int optname,
 			    char __user *optval, int __user *optlen)
 {