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

From: Jianjun Wang <jianjun.wang@mediatek.com>
To: Colin King <colin.king@canonical.com>
Cc: Ryder Lee <ryder.lee@mediatek.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Rob Herring <robh@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	<linux-pci@vger.kernel.org>, <linux-mediatek@lists.infradead.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<kernel-janitors@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH][next] PCI: mediatek-gen3: Add missing null pointer check
Date: Fri, 30 Apr 2021 15:24:54 +0800	[thread overview]
Message-ID: <1619767494.1027.3.camel@mhfsdcap03> (raw)
In-Reply-To: <20210429110040.63119-1-colin.king@canonical.com>

Hi Colin,

On Thu, 2021-04-29 at 12:00 +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.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@canonical.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");