linux-kernel - Re: [PATCH net] net: ll_temac: Fix potential NULL dereference in temac

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Message-ID: <874kkw3drc.fsf@geanix.com>
Date:   Tue, 08 Dec 2020 09:25:59 +0100
From:   Esben Haabendal <esben@...nix.com>
To:     Zhang Changzhong <zhangchangzhong@...wei.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Michal Simek <michal.simek@...inx.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] net: ll_temac: Fix potential NULL dereference in
 temac_probe()

Zhang Changzhong <zhangchangzhong@...wei.com> writes:

> platform_get_resource() may fail and in this case a NULL dereference
> will occur.
>
> Fix it to use devm_platform_ioremap_resource() instead of calling
> platform_get_resource() and devm_ioremap().
>
> This is detected by Coccinelle semantic patch.
>
> @@
> expression pdev, res, n, t, e, e1, e2;
> @@
>
> res = \(platform_get_resource\|platform_get_resource_byname\)(pdev, t, n);
> + if (!res)
> +   return -EINVAL;
> ... when != res == NULL
> e = devm_ioremap(e1, res->start, e2);
>
> Fixes: 8425c41d1ef7 ("net: ll_temac: Extend support to non-device-tree platforms")
> Signed-off-by: Zhang Changzhong <zhangchangzhong@...wei.com>
> ---
>  drivers/net/ethernet/xilinx/ll_temac_main.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
> index 60c199f..0301853 100644
> --- a/drivers/net/ethernet/xilinx/ll_temac_main.c
> +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
> @@ -1351,7 +1351,6 @@ static int temac_probe(struct platform_device *pdev)
>  	struct device_node *temac_np = dev_of_node(&pdev->dev), *dma_np;
>  	struct temac_local *lp;
>  	struct net_device *ndev;
> -	struct resource *res;
>  	const void *addr;
>  	__be32 *p;
>  	bool little_endian;
> @@ -1500,13 +1499,11 @@ static int temac_probe(struct platform_device *pdev)
>  		of_node_put(dma_np);
>  	} else if (pdata) {
>  		/* 2nd memory resource specifies DMA registers */
> -		res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> -		lp->sdma_regs = devm_ioremap(&pdev->dev, res->start,
> -						     resource_size(res));
> -		if (!lp->sdma_regs) {
> +		lp->sdma_regs = devm_platform_ioremap_resource(pdev, 1);
> +		if (IS_ERR(lp->sdma_regs)) {
>  			dev_err(&pdev->dev,
>  				"could not map DMA registers\n");
> -			return -ENOMEM;
> +			return PTR_ERR(lp->sdma_regs);
>  		}
>  		if (pdata->dma_little_endian) {
>  			lp->dma_in = temac_dma_in32_le;

Acked-by: Esben Haabendal <esben@...nix.com>