[PATCH] mtd: core: fix NULL pointer dereference with mtd_check_of_node

[Christian Marangi]

Actually check if mtd dev have a parent to fix NULL pointer dereference
kernel panic in mtd_check_of_node.

Reported-by: kernel test robot <oliver.sang at intel.com>
Fixes: ad9b10d1eaad ("mtd: core: introduce of support for dynamic partitions")
Cc: stable at vger.kernel.org
Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
 drivers/mtd/mtdcore.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 6fafea80fd98..48a357fcf2ed 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -558,8 +558,12 @@ static void mtd_check_of_node(struct mtd_info *mtd)
 	if (dev_of_node(&mtd->dev))
 		return;
 
-	/* Check if a partitions node exist */
+	/* Make sure we have a parent */
 	parent = mtd->parent;
+	if (!parent)
+		return;
+
+	/* Check if a partitions node exist */
 	parent_dn = dev_of_node(&parent->dev);
 	if (!parent_dn)
 		return;
-- 
2.36.1