[PATCH] iommu/rockchip: Check of_find_device_by_node() return value

[Haotian Zhang <vulab@iscas.ac.cn>]

rk_iommu_of_xlate() calls of_find_device_by_node() without
verifying it is non-NULL, which can lead to a NULL pointer
dereference and crash.

Add a check for a NULL return from of_find_device_by_node()
and return -ENODEV upon failure.

Fixes: 5fd577c3eac3 ("iommu/rockchip: Use OF_IOMMU to attach devices automatically")
Signed-off-by: Haotian Zhang <vulab@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 0861dd469bd8..e59d0617574b 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -1153,6 +1153,8 @@ static int rk_iommu_of_xlate(struct device *dev,
 	struct rk_iommudata *data;
 
 	iommu_dev = of_find_device_by_node(args->np);
+	if (!iommu_dev)
+		return -ENODEV;
 
 	data = devm_kzalloc(&iommu_dev->dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
-- 
2.50.1.windows.1