[Ocfs2-devel] [PATCH] ocfs2: fix dlm lock migration crash

[Junxiao Bi <junxiao.bi@oracle.com>]

In the target node of the dlm lock migration, the logic to find
the local dlm lock is wrong, it shouldn't change the loop variable
"lock" in the list_for_each_entry loop. This will cause a NULL-pointer
accessing crash.

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: stable at vger.kernel.org
---
 fs/ocfs2/dlm/dlmrecovery.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
index 01ebfd0..0b9cc88 100644
--- a/fs/ocfs2/dlm/dlmrecovery.c
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -1762,6 +1762,7 @@ static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
 	u8 from = O2NM_MAX_NODES;
 	unsigned int added = 0;
 	__be64 c;
+	int found;
 
 	mlog(0, "running %d locks for this lockres\n", mres->num_locks);
 	for (i=0; i<mres->num_locks; i++) {
@@ -1793,22 +1794,23 @@ static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
 			/* MIGRATION ONLY! */
 			BUG_ON(!(mres->flags & DLM_MRES_MIGRATION));
 
+			found = 0;
 			spin_lock(&res->spinlock);
 			for (j = DLM_GRANTED_LIST; j <= DLM_BLOCKED_LIST; j++) {
 				tmpq = dlm_list_idx_to_ptr(res, j);
 				list_for_each_entry(lock, tmpq, list) {
-					if (lock->ml.cookie != ml->cookie)
-						lock = NULL;
-					else
+					if (lock->ml.cookie == ml->cookie) {
+						found = 1;
 						break;
+					}
 				}
-				if (lock)
+				if (found)
 					break;
 			}
 
 			/* lock is always created locally first, and
 			 * destroyed locally last.  it must be on the list */
-			if (!lock) {
+			if (!found) {
 				c = ml->cookie;
 				mlog(ML_ERROR, "Could not find local lock "
 					       "with cookie %u:%llu, node %u, "
-- 
1.7.9.5