From 7168179fcf25f7812e8541decac686a91359e522 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Tue, 30 Jan 2018 14:30:50 +0200
Subject: [PATCH] ovl: check ERR_PTR() return value from ovl_lookup_real()

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 061701540349 ("ovl: lookup indexed ancestor of lower dir")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/overlayfs/export.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 9df455ca59a8..97a916ea8b86 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -477,8 +477,8 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
 		dput(upper);
 	}
 
-	if (!this)
-		return NULL;
+	if (IS_ERR_OR_NULL(this))
+		return this;
 
 	if (WARN_ON(ovl_dentry_real_at(this, layer->idx) != real)) {
 		dput(this);