[PATCH] iommu/mediatek: check return value after calling platform_get_resource()

[Yang Yingliang]

It will cause null-ptr-deref if platform_get_resource() returns NULL,
we need check the return value.

Fixes: 42d57fc58aeb ("iommu/mediatek: Initialise/Remove for multi bank dev")
Reported-by: Hulk Robot <hulkci at huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang at huawei.com>
---
 drivers/iommu/mtk_iommu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index b2ae84046249..b45b0c1cfff9 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -1174,6 +1174,8 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 
 	banks_num = data->plat_data->banks_num;
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
 	if (resource_size(res) < banks_num * MTK_IOMMU_BANK_SZ) {
 		dev_err(dev, "banknr %d. res %pR is not enough.\n", banks_num, res);
 		return -EINVAL;
-- 
2.25.1