Merge tag 'linux-can-fixes-for-5.13-20210616' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
pull-request: can 2021-06-16

this is a pull request of 4 patches for net/master.

The first patch is by Oleksij Rempel and fixes a Use-after-Free found
by syzbot in the j1939 stack.

The next patch is by Tetsuo Handa and fixes hung task detected by
syzbot in the bcm, raw and isotp protocols.

Norbert Slusarek's patch fixes a infoleak in bcm's struct
bcm_msg_head.

Pavel Skripkin's patch fixes a memory leak in the mcba_usb driver.
====================

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

1 files changed, 48 insertions, 13 deletions

diff --git a/net/can/isotp.c b/net/can/isotp.c
index 253b24417c8e..be6183f8ca11 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -143,10 +143,14 @@ struct isotp_sock {
 	u32 force_tx_stmin;
 	u32 force_rx_stmin;
 	struct tpcon rx, tx;
-	struct notifier_block notifier;
+	struct list_head notifier;
 	wait_queue_head_t wait;
 };
 
+static LIST_HEAD(isotp_notifier_list);
+static DEFINE_SPINLOCK(isotp_notifier_lock);
+static struct isotp_sock *isotp_busy_notifier;
+
 static inline struct isotp_sock *isotp_sk(const struct sock *sk)
 {
 	return (struct isotp_sock *)sk;
@@ -1013,7 +1017,14 @@ static int isotp_release(struct socket *sock)
 	/* wait for complete transmission of current pdu */
 	wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
 
-	unregister_netdevice_notifier(&so->notifier);
+	spin_lock(&isotp_notifier_lock);
+	while (isotp_busy_notifier == so) {
+		spin_unlock(&isotp_notifier_lock);
+		schedule_timeout_uninterruptible(1);
+		spin_lock(&isotp_notifier_lock);
+	}
+	list_del(&so->notifier);
+	spin_unlock(&isotp_notifier_lock);
 
 	lock_sock(sk);
 
@@ -1317,21 +1328,16 @@ static int isotp_getsockopt(struct socket *sock, int level, int optname,
 	return 0;
 }
 
-static int isotp_notifier(struct notifier_block *nb, unsigned long msg,
-			  void *ptr)
+static void isotp_notify(struct isotp_sock *so, unsigned long msg,
+			 struct net_device *dev)
 {
-	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
-	struct isotp_sock *so = container_of(nb, struct isotp_sock, notifier);
 	struct sock *sk = &so->sk;
 
 	if (!net_eq(dev_net(dev), sock_net(sk)))
-		return NOTIFY_DONE;
-
-	if (dev->type != ARPHRD_CAN)
-		return NOTIFY_DONE;
+		return;
 
 	if (so->ifindex != dev->ifindex)
-		return NOTIFY_DONE;
+		return;
 
 	switch (msg) {
 	case NETDEV_UNREGISTER:
@@ -1357,7 +1363,28 @@ static int isotp_notifier(struct notifier_block *nb, unsigned long msg,
 			sk->sk_error_report(sk);
 		break;
 	}
+}
 
+static int isotp_notifier(struct notifier_block *nb, unsigned long msg,
+			  void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+	if (dev->type != ARPHRD_CAN)
+		return NOTIFY_DONE;
+	if (msg != NETDEV_UNREGISTER && msg != NETDEV_DOWN)
+		return NOTIFY_DONE;
+	if (unlikely(isotp_busy_notifier)) /* Check for reentrant bug. */
+		return NOTIFY_DONE;
+
+	spin_lock(&isotp_notifier_lock);
+	list_for_each_entry(isotp_busy_notifier, &isotp_notifier_list, notifier) {
+		spin_unlock(&isotp_notifier_lock);
+		isotp_notify(isotp_busy_notifier, msg, dev);
+		spin_lock(&isotp_notifier_lock);
+	}
+	isotp_busy_notifier = NULL;
+	spin_unlock(&isotp_notifier_lock);
 	return NOTIFY_DONE;
 }
 
@@ -1394,8 +1421,9 @@ static int isotp_init(struct sock *sk)
 
 	init_waitqueue_head(&so->wait);
 
-	so->notifier.notifier_call = isotp_notifier;
-	register_netdevice_notifier(&so->notifier);
+	spin_lock(&isotp_notifier_lock);
+	list_add_tail(&so->notifier, &isotp_notifier_list);
+	spin_unlock(&isotp_notifier_lock);
 
 	return 0;
 }
@@ -1442,6 +1470,10 @@ static const struct can_proto isotp_can_proto = {
 	.prot = &isotp_proto,
 };
 
+static struct notifier_block canisotp_notifier = {
+	.notifier_call = isotp_notifier
+};
+
 static __init int isotp_module_init(void)
 {
 	int err;
@@ -1451,6 +1483,8 @@ static __init int isotp_module_init(void)
 	err = can_proto_register(&isotp_can_proto);
 	if (err < 0)
 		pr_err("can: registration of isotp protocol failed\n");
+	else
+		register_netdevice_notifier(&canisotp_notifier);
 
 	return err;
 }
@@ -1458,6 +1492,7 @@ static __init int isotp_module_init(void)
 static __exit void isotp_module_exit(void)
 {
 	can_proto_unregister(&isotp_can_proto);
+	unregister_netdevice_notifier(&canisotp_notifier);
 }
 
 module_init(isotp_module_init);