[DLM] Telnet to port 21064 can stop all lockspaces

This patch fixes Red Hat bz#245892

Opening a tcp connection from a cluster member to another cluster member
targeting the dlm port it is enough to stop every dlm operation in the cluster.
This means that GFS and rgmanager will hang.

Signed-Off-By: Patrick Caulfield <pcaulfie@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index fc0bff74c61e..73d44f57e24a 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -720,11 +720,17 @@ static int tcp_accept_from_sock(struct connection *con)
                         INIT_WORK(&othercon->rwork, process_recv_sockets);
                         set_bit(CF_IS_OTHERCON, &othercon->flags);
                         newcon->othercon = othercon;
+                        othercon->sock = newsock;
+                        newsock->sk->sk_user_data = othercon;
+                        add_sock(newsock, othercon);
+                        addcon = othercon;
+                }
+                else {
+                        printk("Extra connection from node %d attempted\n", nodeid);
+                        result = -EAGAIN;
+                        up_write(&newcon->sock_sem);
+                        goto accept_err;
                 }
-                othercon->sock = newsock;
-                newsock->sk->sk_user_data = othercon;
-                add_sock(newsock, othercon);
-                addcon = othercon;
         }
         else {
                 newsock->sk->sk_user_data = newcon;