Subject: Re: [PATCH net v4] net: mvpp2: fix possible invalid pointer dereference

From: Jakub Kicinski <[email-masked]>
Date: Tue, 15 Nov 2022 20:28:50 -0800

On Wed, 16 Nov 2022 10:14:37 +0800 Hui Tang wrote:
> It will cause invalid pointer dereference to priv->cm3_base behind,
> if PTR_ERR(priv->cm3_base) in mvpp2_get_sram().
> 
> Fixes: a59d354208a7 ("net: mvpp2: enable global flow control")
> Signed-off-by: Hui Tang <[email-masked]>

Please do not repost new versions so often:

https://www.kernel.org/doc/html/next/process/maintainer-netdev.html#tl-dr

do not use --in-reply-to

> diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> index d98f7e9a480e..efb582b63640 100644
> --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> @@ -7349,6 +7349,7 @@ static int mvpp2_get_sram(struct platform_device *pdev,
>  			  struct mvpp2 *priv)
>  {
>  	struct resource *res;
> +	void __iomem *base;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
>  	if (!res) {
> @@ -7359,9 +7360,11 @@ static int mvpp2_get_sram(struct platform_device *pdev,
>  		return 0;
>  	}
>  
> -	priv->cm3_base = devm_ioremap_resource(&pdev->dev, res);
> +	base = devm_ioremap_resource(&pdev->dev, res);
> +	if (!IS_ERR(base))
> +		priv->cm3_base = base;
>  
> -	return PTR_ERR_OR_ZERO(priv->cm3_base);
> +	return PTR_ERR_OR_ZERO(base);

Use the idiomatic error handling, keep success path un-indented:

	ptr = function();
	if (IS_ERR(ptr))
		return PTR_ERR(ptr);

	priv->bla = ptr;
	return 0;