linux-kernel - Re: [PATCH] iommu/rockchip: check return value of of_find_device_by_node() in rk_iommu_of

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Date:   Thu, 29 Oct 2020 10:08:01 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Yu Kuai <yukuai3@...wei.com>, joro@...tes.org, heiko@...ech.de,
        jeffy.chen@...k-chips.com
Cc:     iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com
Subject: Re: [PATCH] iommu/rockchip: check return value of
 of_find_device_by_node() in rk_iommu_of_xlate()

On 2020-10-29 09:22, Yu Kuai wrote:
> If of_find_device_by_node() failed in rk_iommu_of_xlate(), null pointer
> dereference will be triggered. Thus return error code if
> of_find_device_by_node() failed.

How can that happen? (Given that ".suppress_bind_attrs = true")

Robin.

> Fixes: 5fd577c3eac3("iommu/rockchip: Use OF_IOMMU to attach devices automatically")
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
>   drivers/iommu/rockchip-iommu.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index e5d86b7177de..090d149ef8e9 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -1099,6 +1099,9 @@ static int rk_iommu_of_xlate(struct device *dev,
>   
>   	iommu_dev = of_find_device_by_node(args->np);
>   
> +	if (!iommu_dev)
> +		return -ENODEV;
> +
>   	data->iommu = platform_get_drvdata(iommu_dev);
>   	dev_iommu_priv_set(dev, data);
>   
>