Re: [PATCH v7 4/6] iommu/mediatek: Validate number of phandles associated with "mediatek,larbs"

[Matthias Brugger]

On 18/10/2022 04:42, Yong Wu wrote:
> From: Guenter Roeck <groeck@xxxxxxxxxxxx>
>
> 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@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Signed-off-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
> Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>

Reviewed-by: Matthias Brugger <matthias.bgg@xxxxxxxxx>

> ---
>   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 912322494bc0..9cbff48f03c0 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -1050,6 +1050,8 @@ 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;
> @@ -1068,6 +1070,11 @@ 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);
> @@ -1075,6 +1082,11 @@ 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) {