linux-kernel - Re: [PATCH] reset: uniphier-glue: Fix possible null-ptr-deref

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Message-ID: <32291d3a-25f8-ff5f-d149-180fbb82278d@socionext.com>
Date:   Mon, 14 Nov 2022 10:09:47 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Hui Tang <tanghui20@...wei.com>, p.zabel@...gutronix.de,
        mhiramat@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        weiyongjun1@...wei.com
Subject: Re: [PATCH] reset: uniphier-glue: Fix possible null-ptr-deref

On 2022/11/14 9:49, Hui Tang wrote:
> It will cause null-ptr-deref when resource_size(res) invoked,
> if platform_get_resource() returns NULL.
> 
> Fixes: 499fef09a323 ("reset: uniphier: add USB3 core reset control")
> Signed-off-by: Hui Tang <tanghui20@...wei.com>
> ---
>   drivers/reset/reset-uniphier-glue.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/reset/reset-uniphier-glue.c
> b/drivers/reset/reset-uniphier-glue.c
> index 146fd5d45e99..15abac9fc72c 100644
> --- a/drivers/reset/reset-uniphier-glue.c
> +++ b/drivers/reset/reset-uniphier-glue.c
> @@ -47,7 +47,6 @@ static int uniphier_glue_reset_probe(struct
> platform_device *pdev)
>   	struct device *dev = &pdev->dev;
>   	struct uniphier_glue_reset_priv *priv;
>   	struct resource *res;
> -	resource_size_t size;
>   	int i, ret;
>   
>   	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> @@ -60,7 +59,6 @@ static int uniphier_glue_reset_probe(struct
> platform_device *pdev)
>   		return -EINVAL;
>   
>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	size = resource_size(res);
>   	priv->rdata.membase = devm_ioremap_resource(dev, res);
>   	if (IS_ERR(priv->rdata.membase))
>   		return PTR_ERR(priv->rdata.membase);
> @@ -96,7 +94,7 @@ static int uniphier_glue_reset_probe(struct
> platform_device *pdev)
>   
>   	spin_lock_init(&priv->rdata.lock);
>   	priv->rdata.rcdev.owner = THIS_MODULE;
> -	priv->rdata.rcdev.nr_resets = size * BITS_PER_BYTE;
> +	priv->rdata.rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE;
>   	priv->rdata.rcdev.ops = &reset_simple_ops;
>   	priv->rdata.rcdev.of_node = dev->of_node;
>   	priv->rdata.active_low = true;

Good catch! resource_size() should refer to res after the check.

Reviewed-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>

Thank you,

---
Best Regards
Kunihiko Hayashi