Re: [PATCH net-next v3 5/8] net: mdio: Add SoC-e SWIP MDIO controller driver

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] mdio: null pointer dereference on devm_ioremap failure
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commit b20b4c686880ab360f1cde6275ae5af3a5306146
Author: Vasilij Strassheim <v.strassheim@linutronix.de>

net: mdio: Add SoC-e SWIP MDIO controller driver
    
This commit adds a driver for the MDIO controller integrated into SoC-e
Ethernet switch IP cores. It supports Clause 22 and 45 transactions while
managing shared transaction control registers.

> diff --git a/drivers/net/mdio/mdio-soce.c b/drivers/net/mdio/mdio-soce.c
> new file mode 100644
> index 0000000000000..59c0b3da483eb
> --- /dev/null
> +++ b/drivers/net/mdio/mdio-soce.c
[ ... ]
> +static void __iomem *soce_mdio_iomap(struct device *dev, int index)
> +{
> +	struct resource res;
> +	int ret;
> +
> +	ret = of_address_to_resource(dev->of_node, index, &res);
> +	if (ret)
> +		return IOMEM_ERR_PTR(ret);
> +
> +	return devm_ioremap(dev, res.start, resource_size(&res));
> +}
[ ... ]
> +static int soce_mdio_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct soce_mdio *priv;
> +	struct mii_bus *bus;
> +
> +	bus = devm_mdiobus_alloc_size(dev, sizeof(*priv));
> +	if (!bus)
> +		return -ENOMEM;
> +
> +	priv = bus->priv;
> +	priv->data = soce_mdio_iomap(dev, SOCE_MDIO_DATA_IOMAP_IDX);
> +	if (IS_ERR(priv->data))
> +		return PTR_ERR(priv->data);
> +
> +	priv->ctrl = soce_mdio_iomap(dev, SOCE_MDIO_CTRL_IOMAP_IDX);
> +	if (IS_ERR(priv->ctrl))
> +		return PTR_ERR(priv->ctrl);

[Severity: High]
If devm_ioremap() fails in soce_mdio_iomap(), it returns NULL. Because
IS_ERR(NULL) evaluates to false, will this bypass the error check and allow
the driver to proceed with priv->data and priv->ctrl set to NULL?

If the driver proceeds with NULL pointers, will subsequent PHY accesses 
through soce_mdio_read() and soce_mdio_write() pass those NULL pointers to 
readl() and writel(), leading to a kernel panic?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260923-devel-vstrassheim-soce-dsa-ml-v3-0-ddebafcb9ba7@linutronix.de?part=5