[PATCH 4.4 113/113] ocfs2: fix locking for res->tracking and dlm->tracking_list

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ashish Samant <ashish.samant@xxxxxxxxxx>

commit cbe355f57c8074bc4f452e5b6e35509044c6fa23 upstream.

In dlm_init_lockres() we access and modify res->tracking and
dlm->tracking_list without holding dlm->track_lock.  This can cause list
corruptions and can end up in kernel panic.

Fix this by locking res->tracking and dlm->tracking_list with
dlm->track_lock instead of dlm->spinlock.

Link: http://lkml.kernel.org/r/1529951192-4686-1-git-send-email-ashish.samant@xxxxxxxxxx
Signed-off-by: Ashish Samant <ashish.samant@xxxxxxxxxx>
Reviewed-by: Changwei Ge <ge.changwei@xxxxxxx>
Acked-by: Joseph Qi <jiangqi903@xxxxxxxxx>
Acked-by: Jun Piao <piaojun@xxxxxxxxxx>
Cc: Mark Fasheh <mark@xxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Changwei Ge <ge.changwei@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/ocfs2/dlm/dlmmaster.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -589,9 +589,9 @@ static void dlm_init_lockres(struct dlm_
 
 	res->last_used = 0;
 
-	spin_lock(&dlm->spinlock);
+	spin_lock(&dlm->track_lock);
 	list_add_tail(&res->tracking, &dlm->tracking_list);
-	spin_unlock(&dlm->spinlock);
+	spin_unlock(&dlm->track_lock);
 
 	memset(res->lvb, 0, DLM_LVB_LEN);
 	memset(res->refmap, 0, sizeof(res->refmap));