[PATCH] ocfs2:fix potential Null Ptr Dereference

[Yizhuo]

Inside function o2hb_region_blocks_store(), to_o2hb_region()
could return NULL but there's no check before its dereference,
which is potentially unsafe.

Signed-off-by: Yizhuo <yzhai003@xxxxxxx>
---
 fs/ocfs2/cluster/heartbeat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index a368350d4c27..93f2b540f245 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -1628,7 +1628,7 @@ static ssize_t o2hb_region_blocks_store(struct config_item *item,
 	unsigned long tmp;
 	char *p = (char *)page;
 
-	if (reg->hr_bdev)
+	if (!reg || reg->hr_bdev)
 		return -EINVAL;
 
 	tmp = simple_strtoul(p, &p, 0);
-- 
2.17.1