[PATCH] iommu/rockchip: Add missing check for of_find_device_by_node

[Chen Ni]

Add check for the return value of of_find_device_by_node() and return
the error if it fails in order to avoid NULL pointer dereference.

Fixes: 5fd577c3eac3 ("iommu/rockchip: Use OF_IOMMU to attach devices automatically")
Signed-off-by: Chen Ni <nichen at iscas.ac.cn>
---
 drivers/iommu/rockchip-iommu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index 4b369419b32c..1225c1df6ef6 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -1152,6 +1152,8 @@ static int rk_iommu_of_xlate(struct device *dev,
 		return -ENOMEM;
 
 	iommu_dev = of_find_device_by_node(args->np);
+	if (!iommu_dev)
+		return -ENODEV;
 
 	data->iommu = platform_get_drvdata(iommu_dev);
 	data->iommu->domain = &rk_identity_domain;
-- 
2.25.1