Re: [PATCH] iommu/mediatek: fix leaked of_node references

[Matthias Brugger]

On 17/04/2019 04:41, Wen Yang wrote:
> The call to of_parse_phandle returns a node pointer with refcount
> incremented thus it must be explicitly decremented after the last
> usage.
> 
> 581 static int mtk_iommu_probe(struct platform_device *pdev)
> 582 {
>     ...
> 626         for (i = 0; i < larb_nr; i++) {
> 627                 struct device_node *larbnode;
>     ...
> 631                 larbnode = of_parse_phandle(...);
> 632                 if (!larbnode)
> 633                         return -EINVAL;
> 634
> 635                 if (!of_device_is_available(larbnode))
> 636                         continue;             ---> leaked here
> 637
>     ...
> 643                 if (!plarbdev)
> 644                         return -EPROBE_DEFER; ---> leaked here
>     ...
> 647                 component_match_add_release(dev, &match, release_of,
> 648                                             compare_of, larbnode);
>                                    ---> release_of will call of_node_put
> 649         }
>     ...
> 650
> 
> Detected by coccinelle with the following warnings:
> ./drivers/iommu/mtk_iommu.c:644:3-9: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 631, but without a corresponding object release within this function.
> 
> Signed-off-by: Wen Yang <wen.yang99@xxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx>
> Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-mediatek@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx

Reviewed-by: Matthias Brugger <mbrugger@xxxxxxxx>

> ---
>  drivers/iommu/mtk_iommu.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index de3e022..b66d11b 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -632,16 +632,20 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>  		if (!larbnode)
>  			return -EINVAL;
>  
> -		if (!of_device_is_available(larbnode))
> +		if (!of_device_is_available(larbnode)) {
> +			of_node_put(larbnode);
>  			continue;
> +		}
>  
>  		ret = of_property_read_u32(larbnode, "mediatek,larb-id", &id);
>  		if (ret)/* The id is consecutive if there is no this property */
>  			id = i;
>  
>  		plarbdev = of_find_device_by_node(larbnode);
> -		if (!plarbdev)
> +		if (!plarbdev) {
> +			of_node_put(larbnode);
>  			return -EPROBE_DEFER;
> +		}
>  		data->smi_imu.larb_imu[id].dev = &plarbdev->dev;
>  
>  		component_match_add_release(dev, &match, release_of,
>