linux-kernel - Re: [PATCH][next] PCI: mediatek-gen3: Add missing null pointer check

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Date:   Fri, 30 Apr 2021 15:24:54 +0800
From:   Jianjun Wang <jianjun.wang@...iatek.com>
To:     Colin King <colin.king@...onical.com>
CC:     Ryder Lee <ryder.lee@...iatek.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-pci@...r.kernel.org>, <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kernel-janitors@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][next] PCI: mediatek-gen3: Add missing null pointer check

Hi Colin,

On Thu, 2021-04-29 at 12:00 +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> The call to platform_get_resource_byname can potentially return null, so
> add a null pointer check to avoid a null pointer dereference issue.
> 
> Addresses-Coverity: ("Dereference null return")
> Fixes: 441903d9e8f0 ("PCI: mediatek-gen3: Add MediaTek Gen3 driver for MT8192")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/pci/controller/pcie-mediatek-gen3.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
> index 20165e4a75b2..3c5b97716d40 100644
> --- a/drivers/pci/controller/pcie-mediatek-gen3.c
> +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
> @@ -721,6 +721,8 @@ static int mtk_pcie_parse_port(struct mtk_pcie_port *port)
>  	int ret;
>  
>  	regs = platform_get_resource_byname(pdev, IORESOURCE_MEM, "pcie-mac");
> +	if (!regs)
> +		return -EINVAL;

Thanks for your patch.

devm_ioremap_resource() will check and decode this null pointer
dereference error, so I don't think we need to check here.

Thanks.

>  	port->base = devm_ioremap_resource(dev, regs);
>  	if (IS_ERR(port->base)) {
>  		dev_err(dev, "failed to map register base\n");