Ocfs2 devel - Feb 2014 - [PATCH] ocfs2: fix null pointer dereference when access dlm_state before launching dlm thread

From: Zongxun Wang <wangzongxun at huawei.com>

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 at huawei.com>
Signed-off-by: Joseph Qi <joseph.qi at huawei.com>
---
 fs/ocfs2/dlm/dlmdomain.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index 33660a4..1307a8c 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -1877,19 +1877,19 @@ static int dlm_join_domain(struct dlm_ctxt *dlm)
 		goto bail;
 	}

-	status = dlm_debug_init(dlm);
+	status = dlm_launch_thread(dlm);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;
 	}

-	status = dlm_launch_thread(dlm);
+	status = dlm_launch_recovery_thread(dlm);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;
 	}

-	status = dlm_launch_recovery_thread(dlm);
+	status = dlm_debug_init(dlm);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;
-- 
1.8.4.3