Re: [PATCH -next] gpio: ath79: Fix potential NULL dereference in ath79_gpio_probe()

[Alban <albeu@free.fr>]

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On Thu, 4 Jan 2018 06:31:23 +0000
Wei Yongjun <weiyongjun1@huawei.com> wrote:

> platform_get_resource() may return NULL, add proper
> check to avoid potential NULL dereferencing.
> 
> 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(e1, res->start, e2);
> 
> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
> ---
>  drivers/gpio/gpio-ath79.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpio/gpio-ath79.c b/drivers/gpio/gpio-ath79.c
> index a757171..0bebcba 100644
> --- a/drivers/gpio/gpio-ath79.c
> +++ b/drivers/gpio/gpio-ath79.c
> @@ -258,6 +258,8 @@ static int ath79_gpio_probe(struct platform_device *pdev)
>  	}
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;
>  	ctrl->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
>  	if (!ctrl->base)
>  		return -ENOMEM;

This fix is needed, however this patch is not against the current
version. The current version use res in a call to devm_ioremap_nocache()
and not devm_ioremap().

Alban

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