can: bcm/raw/isotp: use per module netdevice notifier

syzbot is reporting hung task at register_netdevice_notifier() [1] and
unregister_netdevice_notifier() [2], for cleanup_net() might perform
time consuming operations while CAN driver's raw/bcm/isotp modules are
calling {register,unregister}_netdevice_notifier() on each socket.

Change raw/bcm/isotp modules to call register_netdevice_notifier() from
module's __init function and call unregister_netdevice_notifier() from
module's __exit function, as with gw/j1939 modules are doing.

Link: https://syzkaller.appspot.com/bug?id=391b9498827788b3cc6830226d4ff5be87107c30 [1]
Link: https://syzkaller.appspot.com/bug?id=1724d278c83ca6e6df100a2e320c10d991cf2bce [2]
Link: https://lore.kernel.org/r/54a5f451-05ed-f977-8534-79e7aa2bcc8f@i-love.sakura.ne.jp
Cc: linux-stable <stable@vger.kernel.org>
Reported-by: syzbot <syzbot+355f8edb2ff45d5f95fa@syzkaller.appspotmail.com>
Reported-by: syzbot <syzbot+0f1827363a305f74996f@syzkaller.appspotmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: syzbot <syzbot+355f8edb2ff45d5f95fa@syzkaller.appspotmail.com>
Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

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);