From 181a9a043b5424f2e6451297bbc27b196fe88475 Mon Sep 17 00:00:00 2001
From: Zongxun Wang <wangzongxun@huawei.com>
Date: Thu, 3 Apr 2014 14:46:45 -0700
Subject: [PATCH] ocfs2: fix null pointer dereference when access dlm_state
 before launching dlm thread

When mounting an ocfs2 volume, it will firstly generate a file
/sys/kernel/debug/o2dlm/<uuid>/dlm_state, and then launch the dlm thread.
So the following situation will cause a null pointer dereference.
dlm_debug_init -> access file dlm_state which will call dlm_state_print ->
dlm_launch_thread

Move dlm_debug_init after dlm_launch_thread and dlm_launch_recovery_thread
can fix this issue.

Signed-off-by: Zongxun Wang <wangzongxun@huawei.com>
Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/ocfs2/dlm/dlmdomain.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index 33660a4a52fa..1307a8cff8db 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -1877,12 +1877,6 @@ static int dlm_join_domain(struct dlm_ctxt *dlm)
 		goto bail;
 	}
 
-	status = dlm_debug_init(dlm);
-	if (status < 0) {
-		mlog_errno(status);
-		goto bail;
-	}
-
 	status = dlm_launch_thread(dlm);
 	if (status < 0) {
 		mlog_errno(status);
@@ -1895,6 +1889,12 @@ static int dlm_join_domain(struct dlm_ctxt *dlm)
 		goto bail;
 	}
 
+	status = dlm_debug_init(dlm);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
 	dlm->dlm_worker = create_singlethread_workqueue("dlm_wq");
 	if (!dlm->dlm_worker) {
 		status = -ENOMEM;