net: x25: fix one potential use-after-free issue

The function x25_init is not properly unregister related resources
on error handler.It is will result in kernel oops if x25_init init
failed, so add properly unregister call on error handler.

Also, i adjust the coding style and make x25_register_sysctl properly
return failure.

Signed-off-by: linzhang <xiaolou4617@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 8 deletions

diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 8b911c29860e..5a1a98df3499 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -1791,32 +1791,40 @@ void x25_kill_by_neigh(struct x25_neigh *nb)
 
 static int __init x25_init(void)
 {
-	int rc = proto_register(&x25_proto, 0);
+	int rc;
 
-	if (rc != 0)
+	rc = proto_register(&x25_proto, 0);
+	if (rc)
 		goto out;
 
 	rc = sock_register(&x25_family_ops);
-	if (rc != 0)
+	if (rc)
 		goto out_proto;
 
 	dev_add_pack(&x25_packet_type);
 
 	rc = register_netdevice_notifier(&x25_dev_notifier);
-	if (rc != 0)
+	if (rc)
 		goto out_sock;
 
-	pr_info("Linux Version 0.2\n");
+	rc = x25_register_sysctl();
+	if (rc)
+		goto out_dev;
 
-	x25_register_sysctl();
 	rc = x25_proc_init();
-	if (rc != 0)
-		goto out_dev;
+	if (rc)
+		goto out_sysctl;
+
+	pr_info("Linux Version 0.2\n");
+
 out:
 	return rc;
+out_sysctl:
+	x25_unregister_sysctl();
 out_dev:
 	unregister_netdevice_notifier(&x25_dev_notifier);
 out_sock:
+	dev_remove_pack(&x25_packet_type);
 	sock_unregister(AF_X25);
 out_proto:
 	proto_unregister(&x25_proto);