iommu/mediatek: Validate number of phandles associated with "mediatek,larbs"

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>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20221018024258.19073-5-yong.wu@mediatek.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index e0c669b75271d8c346f48730382d6cdfce058125..41e96da6160f3bcbedb99cfde6502277f1e08d43 100644 (file)
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -1062,6 +1062,8 @@ 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;
@@ -1080,6 +1082,11 @@ 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);
@@ -1087,6 +1094,11 @@ 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) {