[-next] dmaengine: sprd: Fix potential NULL dereference in sprd_dma_probe()

[Lars-Peter Clausen <lars@metafoo.de>]

On 05/07/2018 03:40 AM, Wei Yongjun wrote:
> platform_get_resource() may fail and return NULL, so we should
> better check it's return value to avoid a NULL pointer dereference
> a bit later in the code.
> 
> This is detected by Coccinelle semantic patch.
> 
> @@
> expression pdev, res, n, t, e, e1, e2;
> @@
> 
> res = platform_get_resource(pdev, t, n);
> + if (!res)
> +   return -EINVAL;
> ... when != res == NULL
> e = devm_ioremap_nocache(e1, res->start, e2);
> 
> Fixes: 9b3b8171f7f4 ("dmaengine: sprd: Add Spreadtrum DMA driver")
> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
> ---
>  drivers/dma/sprd-dma.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/dma/sprd-dma.c b/drivers/dma/sprd-dma.c
> index ccdeb8f..dba7a17 100644
> --- a/drivers/dma/sprd-dma.c
> +++ b/drivers/dma/sprd-dma.c
> @@ -807,6 +807,8 @@ static int sprd_dma_probe(struct platform_device *pdev)
>  	}
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;
>  	sdev->glb_base = devm_ioremap_nocache(&pdev->dev, res->start,
>  					      resource_size(res));

I think a better improvement would be to replace this with
devm_ioremap_resource() which has the NULL pointer check and some other
things built-in.
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