[PATCH v6 4/6] iommu/mediatek: Validate number of phandles associated with "mediatek,larbs"

[Yong Wu <yong.wu@mediatek.com>]

From: Guenter Roeck <groeck@chromium.org>

Fix the smatch warnings:
drivers/iommu/mtk_iommu.c:878 mtk_iommu_mm_dts_parse() error: uninitialized
symbol 'larbnode'.

If someone abuse the dtsi node(Don't follow the definition of dt-binding),
for example "mediatek,larbs" is provided as boolean property, "larb_nr"
will be zero and cause abnormal.

To fix this problem and improve the code safety, add some checking
for the invalid input from dtsi, e.g. checking the larb_nr/larbid valid
range, and avoid "mediatek,larb-id" property conflicts in the smi-larb
nodes.

Fixes: d2e9a1102cfc ("iommu/mediatek: Contain MM IOMMU flow with the MM TYPE")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/iommu/mtk_iommu.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 97b721006a47..01b31b09bd8d 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -1048,6 +1048,8 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 	larb_nr = of_count_phandle_with_args(dev->of_node, "mediatek,larbs", NULL);
 	if (larb_nr < 0)
 		return larb_nr;
+	if (larb_nr == 0 || larb_nr > MTK_LARB_NR_MAX)
+		return -EINVAL;
 
 	for (i = 0; i < larb_nr; i++) {
 		u32 id;
@@ -1066,6 +1068,11 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 		ret = of_property_read_u32(larbnode, "mediatek,larb-id", &id);
 		if (ret)/* The id is consecutive if there is no this property */
 			id = i;
+		if (id >= MTK_LARB_NR_MAX) {
+			of_node_put(larbnode);
+			ret = -EINVAL;
+			goto err_larbdev_put;
+		}
 
 		plarbdev = of_find_device_by_node(larbnode);
 		of_node_put(larbnode);
@@ -1073,6 +1080,11 @@ static int mtk_iommu_mm_dts_parse(struct device *dev, struct component_match **m
 			ret = -ENODEV;
 			goto err_larbdev_put;
 		}
+		if (data->larb_imu[id].dev) {
+			platform_device_put(plarbdev);
+			ret = -EEXIST;
+			goto err_larbdev_put;
+		}
 		data->larb_imu[id].dev = &plarbdev->dev;
 
 		if (!plarbdev->dev.driver) {
-- 
2.18.0